Aminocyclohexanes as Dipeptidyl Peptidase-Iv Inhibitors for the Treatment or Prevention of Diabetes

ABSTRACT

The present invention is directed to novel substituted aminocyclohexanes which are inhibitors of the dipeptidyl peptidase-IV enzyme (“DPP-IV inhibitors”) and which are useful in the treatment or prevention of diseases in which the dipeptidyl peptidase-IV enzyme is involved, such as diabetes and particularly Type 2 diabetes. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which the dipeptidyl peptidase-IV enzyme is involved.

FIELD OF THE INVENTION

The present invention relates to novel substituted aminocyclohexaneswhich are inhibitors of the dipeptidyl peptidase-IV enzyme (“DPP-IVinhibitors”) and which are useful in the treatment or prevention ofdiseases in which the dipeptidyl peptidase-IV enzyme is involved, suchas diabetes and particularly Type 2 diabetes. The invention is alsodirected to pharmaceutical compositions comprising these compounds andthe use of these compounds and compositions in the prevention ortreatment of such diseases in which the dipeptidyl peptidase-IV enzymeis involved.

BACKGROUND OF THE INVENTION

Diabetes refers to a disease process derived from multiple causativefactors and characterized by elevated levels of plasma glucose orhyperglycemia in the fasting state or after administration of glucoseduring an oral glucose tolerance test. Persistent or uncontrolledhyperglycemia is associated with increased and premature morbidity andmortality. Often abnormal glucose homeostasis is associated bothdirectly and indirectly with alterations of the lipid, lipoprotein andapolipoprotein metabolism and other metabolic and hemodynamic disease.Therefore patients with Type 2 diabetes mellitus are at especiallyincreased risk of macrovascular and microvascular complications,including coronary heart disease, stroke, peripheral vascular disease,hypertension, nephropathy, neuropathy, and retinopathy. Therefore,therapeutical control of glucose homeostasis, lipid metabolism andhypertension are critically important in the clinical management andtreatment of diabetes mellitus.

There are two generally recognized forms of diabetes. In Type 1diabetes, or insulin-dependent diabetes mellitus (IDDM), patientsproduce little or no insulin, the hormone which regulates glucoseutilization. In Type 2 diabetes, or noninsulin dependent diabetesmellitus (NIDDM), patients often have plasma insulin levels that are thesame or even elevated compared to nondiabetic subjects; however, thesepatients have developed a resistance to the insulin stimulating effecton glucose and lipid metabolism in the main insulin-sensitive tissues,which are muscle, liver and adipose tissues, and the plasma insulinlevels, while elevated, are insufficient to overcome the pronouncedinsulin resistance.

Insulin resistance is not primarily due to a diminished number ofinsulin receptors but to a post-insulin receptor binding defect that isnot yet understood. This resistance to insulin responsiveness results ininsufficient insulin activation of glucose uptake, oxidation and storagein muscle and inadequate insulin repression of lipolysis in adiposetissue and of glucose production and secretion in the liver.

The available treatments for Type 2 diabetes, which have not changedsubstantially in many years, have recognized limitations. While physicalexercise and reductions in dietary intake of calories will dramaticallyimprove the diabetic condition, compliance with this treatment is verypoor because of well-entrenched sedentary lifestyles and excess foodconsumption, especially of foods containing high amounts of saturatedfat. Increasing the plasma level of insulin by administration ofsulfonylureas (e.g. tolbutamide and glipizide) or meglitinide, whichstimulate the pancreatic {tilde over (□)} cells to secrete more insulin,and/or by injection of insulin when sulfonylureas or meglitinide becomeineffective, can result in insulin concentrations high enough tostimulate the very insulin-resistant tissues. However, dangerously lowlevels of plasma glucose can result from administration of insulin orinsulin secretagogues (sulfonylureas or meglitinide), and an increasedlevel of insulin resistance due to the even higher plasma insulin levelscan occur. The biguanides increase insulin sensitivity resulting in somecorrection of hyperglycemia. However, the two biguanides, phenformin andmetformin, can induce lactic acidosis and nausea/diarrhea. Metformin hasfewer side effects than phenformin and is often prescribed for thetreatment of Type 2 diabetes.

The glitazones (i.e. 5-benzylthiazolidine-2,4-diones) are a morerecently described class of compounds with potential for amelioratingmany symptoms of Type 2 diabetes. These agents substantially increaseinsulin sensitivity in muscle, liver and adipose tissue in severalanimal models of Type 2 diabetes resulting in partial or completecorrection of the elevated plasma levels of glucose without occurrenceof hypoglycemia. The glitazones that are currently marketed are agonistsof the peroxisome proliferator activated receptor (PPAR), primarily thePPAR-gamma subtype. PPAR-gainma agonism is generally believed to beresponsible for the improved insulin sensititization that is observedwith the glitazones. Newer PPAR agonists that are being tested fortreatment of Type II diabetes are agonists of the alpha, gamma or deltasubtype, or a combination of these, and in many cases are chemicallydifferent from the glitazones (i.e., they are not thiazolidinediones).Serious side effects (e.g. liver toxicity) have occurred with some ofthe glitazones, such as troglitazone.

Additional methods of treating the disease are still underinvestigation. New biochemical approaches that have been recentlyintroduced or are still under development include treatment withalpha-glucosidase inhibitors (e.g. acarbose) and protein tyrosinephosphatase-1B (PTP-1B) inhibitors.

Compounds that are inhibitors of the dipeptidyl peptidase-IV (“DPP-IV”)enzyme are also under investigation as drugs that may be useful in thetreatment of diabetes, and particularly Type 2 diabetes. See for exampleWO 97/40832, WO 98/19998, U.S. Pat. No. 5,939,560, Bioorg. Med. Chem.Lett., 6: 1163-1166 (1996); and Bioorg. Med. Chem. Lett. 6: 2745-2748(1996). The usefulness of DPP-IV inhibitors in the treatment of Type 2diabetes is based on the fact that DPP-IV in vivo readily inactivatesglucagon like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP).GLP-1 and GIP are incretins and are produced when food is consumed. Theincretins stimulate production of insulin. Inhibition of DPP-IV leads todecreased inactivation of the incretins, and this in turn results inincreased effectiveness of the incretins in stimulating production ofinsulin by the pancreas. DPP-IV inhibition therefore results in anincreased level of serum insulin. Advantageously, since the incretinsare produced by the body only when food is consumed, DPP-IV inhibitionis not expected to increase the level of insulin at inappropriate times,such as between meals, which can lead to excessively low blood sugar(hypoglycemia). Inhibition of DPP-IV is therefore expected to increaseinsulin without increasing the risk of hypoglycemia, which is adangerous side effect associated with the use of insulin secretagogues.

DPP-IV inhibitors also have other therapeutic utilities, as discussedherein. DPP-IV inhibitors have not been studied extensively to date,especially for utilities other than diabetes. New compounds are neededso that improved DPP-IV inhibitors can be found for the treatment ofdiabetes and potentially other diseases and conditions. The therapeuticpotential of DPP-IV inhibitors for the treatment of Type 2 diabetes isdiscussed by D. J. Drucker in Exp. Opin. Invest. Drugs, 12: 87-100(2003) and by K. Augustyns, et al., in Exp. Opin. Ther. Patents, 13:499-510 (2003).

SUMMARY OF THE INVENTION

The present invention is directed to novel substituted aminocyclohexaneswhich are inhibitors of the dipeptidyl peptidase-IV enzyme (“DPP-IVinhibitors”) and which are useful in the treatment or prevention ofdiseases in which the dipeptidyl peptidase-IV enzyme is involved, suchas diabetes and particularly Type 2 diabetes. The invention is alsodirected to pharmaceutical compositions comprising these compounds andthe use of these compounds and compositions in the prevention ortreatment of such diseases in which the dipeptidyl peptidase-IV enzymeis involved.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to substituted aminocyclohexanes useful asinhibitors of dipeptidyl peptidase-IV. Compounds of the presentinvention are described by structural formula I:

or a pharmaceutically acceptable salt thereof; whereineach n is independently 0, 1, 2, or 3;X is selected from the group consisting of a bond, C═O, SO₂, CO₂, CONHand CONR²;Ar is phenyl unsubstituted or substituted with one to five R¹substituents;each R¹ is independently selected from the group consisting of

-   halogen,-   cyano,-   hydroxy,-   C₁₋₆ alkyl, unsubstituted or substituted with one to five halogens,-   C₁₋₆ alkoxy, unsubstituted or substituted with one to five halogens,-   carboxy,-   C₁₋₆ alkyloxycarbonyl,-   amino,-   NHR²,-   NR²R²,-   NHSO₂R²,-   NR²SO₂R²,-   NHCOR²,-   NR²COR²,-   NHCO₂R²,-   NR²CO₂R²,-   SO₂R²,-   SO₂NH₂,-   SO₂NHR₂, and-   SO₂NR²R²;    each R² is independently C₁₋₆ alkyl, unsubstituted or substituted    with one to five substituents independently selected from halogen,    CO₂H, and C₁₋₆ alkyloxycarbonyl;    each R³ and R⁴ is independently selected from the group consisting    of hydrogen,-   C₁₋₁₀ alkyl, wherein alkyl is unsubstituted or substituted with one    to five substituents independently selected from halogen or hydroxy,-   C₂₋₁₀ alkenyl, wherein alkenyl is unsubstituted or substituted with    one to five substituents independently selected from halogen or    hydroxy,-   (CH₂)_(n)-aryl, wherein aryl is unsubstituted or substituted with    one to five substituents independently selected from R⁶,-   (CH₂)_(n)-heteroaryl, wherein heteroaryl is unsubstituted or    substituted with one to three substituents independently selected    from R⁶,-   (CH₂)_(n)-heterocyclyl, wherein heterocyclyl is unsubstituted or    substituted with one to three substituents independently selected    from oxo and R⁶,-   (CH₂)_(n)-C₃₋₆ cycloalkyl, wherein cycloalkyl is unsubstituted or    substituted with one to three substituents independently selected    from R⁶;    wherein any individual methylene (CH₂) carbon atom in (CH₂)_(n) is    unsubstituted or substituted with one to two groups independently    selected from halogen, hydroxy, C₁₋₄ alkyl, and C₁₋₄ alkoxy, wherein    alkyl and alkoxy are unsubstituted or substituted with one to five    halogens;    or, when X is a bond, R³ and R⁴ together with the nitrogen atom to    which they are attached form a 4- to 7-membered monocyclic    heterocyclic ring optionally containing an additional heteroatom    selected from O, S, N, and NH, said heterocyclic ring being    unsubstituted or substituted with one to three R^(a) substituents    independently selected from oxo, hydroxy, halogen, C₃₋₆ cycloalkyl,    C₁₋₄ alkoxy, and C₁₋₄ alkyl, wherein cycloalkyl, alkyl and alkoxy    are unsubstituted or substituted with one to five fluorines; and    said heterocyclic ring being optionally fused with a 5- to    6-membered saturated, partially unsaturated, or aromatic carbocyclic    ring or a 5- to 6-membered saturated, partially unsaturated, or    aromatic heterocyclic ring containing one to three heteroatoms    selected from O, S, N, and NH, said fused ring being unsubstituted    or substituted with one to four R^(b) substituents independently    selected from oxo, hydroxy, amino, halogen, C₃₋₆ cycloalkyl, C₁₋₄    alkyl, and C₁₋₄ alkoxy, wherein cycloalkyl, alkyl and alkoxy are    unsubstituted or substituted with one to five fluorines;    each R⁶ is independently selected from the group consisting of-   hydroxy,-   halogen,-   cyano,-   CO₂H,-   NR⁷R⁸,-   CONR⁷R⁸,-   OCONR⁷R⁸,-   SO₂NR⁷R⁸,-   SO₂R⁹,-   NR¹⁰SO₂R⁹,-   NR¹⁰CONR⁷R⁸,-   NR¹⁰COR⁹,-   NR¹⁰CO²R⁹,-   C₁₋₆ alkyloxycarbonyl,-   C₁₋₆ alkyl, and-   C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted or    substituted with one to five halogens;    R⁷ and R⁸ are each independently selected from the group consisting    of-   hydrogen,-   (CH₂)_(n)-phenyl,-   (CH₂)_(n)-C₃₋₆ cycloalkyl, and-   C₁₋₆ alkyl, wherein alkyl is unsubstituted or substituted with one    to five substituents independently selected from halogen and hydroxy    and wherein phenyl and cycloalkyl are unsubstituted or substituted    with one to five substituents independently selected from halogen,    hydroxy, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are    unsubstituted or substituted with one to five halogens;    or R⁷ and R⁸ together with the nitrogen atom to which they are    attached form a heterocyclic ring selected from azetidine,    pyrrolidine, piperidine, piperazine, and morpholine wherein said    heterocyclic ring is unsubstituted or substituted with one to three    substituents independently selected from halogen, hydroxy, C₁₋₆    alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted    or substituted with one to five halogens;    each R⁹ is independently C₁₋₆ alkyl, wherein alkyl is unsubstituted    or substituted with one to five substituents independently selected    from halogen and hydroxyl; and    R¹⁰ is hydrogen or R⁹.

In one embodiment of the compounds of the present invention, each R¹ isindependently selected from the group consisting of fluorine, chlorine,bromine, methyl, trifluoromethyl, and trifluoromethoxy.

In a second embodiment of the compounds of the present invention, X is abond and R³ and R⁴ together with the nitrogen atom to which they areattached form an optionally fused nitrogen-containing heterocyclic ringselected from the group consisting of:

wherein the optionally fused nitrogen-containing heterocyclic ring isunsubstituted or substituted with R^(a) and R^(b) substituents asdefined above.

In a class of this second embodiment, the nitrogen-containingheterocyclic ring is selected from the group consisting of:

unsubstituted or substituted with R^(a) and R^(b) substituents asdefined above.

In a third embodiment of the compounds of the present invention, thereare provided compounds of structural formulae Ia and Ib of the indicatedstereochemical configuration having a trans orientation of the Ar andNH2 substituents on the two stereogenic cyclohexane carbon atoms markedwith an *:

wherein Ar, X, R³ and R⁴ are as described above.

In a class of this third embodiment, there are provided compounds ofstructural formula Ia of the indicated absolute stereochemicalconfiguration having a trans orientation of the Ar and NH₂ substituentson the two stereogenic cyclohexane carbon atoms marked with an *:

In a second class of this third embodiment, there are provided compoundsof structural formulae Ic and Id of the indicated stereochemnicalconfiguration having a trans orientation of the Ar and NH² substituents,a trans orientation of the Ar and N(R⁴)—X—R³ substituents, and a cisorientation of the NH₂ and N(R⁴)—X—R³ substituents on the threestereogenic cyclohexane carbon atoms marked with an *:

In a subclass of this class, there are provided compounds of structuralformula Ic of the indicated absolute stereochemical configuration havinga trans orientation of the Ar and NH² substituents, a traits orientationof the Ar and N(R⁴)—X—R³ substituents, and a cis orientation of the NH²and N(R⁴)—X—R³ substituents on the three stereogenic cyclohexane carbonatoms marked with an *:

In a subclass of this subclass, X is a bond and R³ and R⁴ together withthe nitrogen atom to which they are attached form an optionally fusednitrogen-containing heterocyclic ring selected from the group consistingof:

unsubstituted or substituted with R^(a) and R^(b) substituents asdefined above.

In a third class of this third embodiment, there are provided compoundsof structural formulae Ie and If of the indicated stereochemicalconfiguration having a trains orientation of the Ar and NH₂substituents, a cis orientation of the Ar and N(R⁴)—X—R³ substituents,and a traits orientation of the NH₂ and N(R⁴)—X—R³ substituents on thethree stereogenic cyclohexane carbon atoms marked with an *:

In a subclass of this class, there are provided compounds of structuralformula Ie of the indicated absolute stereocherrical configurationhaving a trans orientation of the Ar and NH₂ substituents, a cisorientation of the Ar and N(R⁴)—X—R³ substituents, and a transorientation of the NH₂ and N(R⁴)—X—R³ substituents on the threestereogenic cyclohexane carbon atoms marked with an *:

In a subclass of this subclass, X is a bond and R³ and R⁴ together withthe nitrogen atom to which they are attached form an optionally fusednitrogen-containing heterocyclic ring selected from the group consistingof:

unsubstituted or substituted with R^(a) and R^(b) substituents asdefined above.

Nonlimiting examples of compounds of the present invention that areuseful as dipeptidyl peptidase-IV inhibitors are the followingstructures having the indicated absolute stereochemical configurationsat the three stereogenic cyclohexane carbon atoms:

or a pharmaceutically acceptable salt thereof.

As used herein the following definitions are applicable. “Alkyl”, aswell as other groups having the prefix “alk”, such as alkoxy andalkanoyl, means carbon chains which may be linear or branched, andcombinations thereof, unless the carbon chain is defined otherwise.Examples of alkyl groups include methyl, ethyl, propyl, isopropyl,butyl, sec- and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and thelike. Where the specified number of carbon atoms permits, e.g., fromC₃₋₁₀, the term alkyl also includes cycloalkyl groups, and combinationsof linear or branched alkyl chains combined with cycloalkyl structures.When no number of carbon atoms is specified, C₁₋₆ is intended.

“Cycloalkyl” is a subset of alkyl and means a saturated carbocyclic ringhaving a specified number of carbon atoms. Examples of cycloalkylinclude cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, and the like. A cycloalkyl group generally is monocyclicunless stated otherwise. Cycloalkyl groups are saturated unlessotherwise defined.

The term “alkoxy” refers to straight or branched chain alkoxides of thenumber of carbon atoms specified (e.g., C₁₋₁₀ alkoxy), or any numberwithin this range [i.e., methoxy (MeO—), ethoxy, isopropoxy, etc.].

The term “alkylthio” refers to straight or branched chain alkylsulfidesof the number of carbon atoms specified (e.g., C₁₋₁₀ alkylthio), or anynumber within this range [i.e., methylthio (MeS—), ethylthio,isopropylthio, etc.].

The term “alkylamino” refers to straight or branched alkylamines of thenumber of carbon atoms specified (e.g., C₁₋₆ alkylamino), or any numberwithin this range [i.e., methylamino, ethylamino, isopropylamino,t-butylamino, etc.].

The term “alkylsulfonyl” refers to straight or branched chainalkylsulfones of the number of carbon atoms specified (e.g., C₁₋₆alkylsulfonyl), or any number within this range [i.e., methylsulfonyl(MeSO₂—), ethylsulfonyl, isopropylsulfonyl, etc.].

The term “alkyloxycarbonyl” refers to straight or branched chain estersof a carboxylic acid derivative of the present invention of the numberof carbon atoms specified (e.g., C₁₋₆ alkyloxycarbonyl), or any numberwithin this range [i.e., methyloxycarbonyl (MeOCO—), ethyloxycarbonyl,or butyloxycarbonyl].

“Aryl” means a mono- or polycyclic aromatic ring system containingcarbon ring atoms. The preferred aryls are monocyclic or bicyclic 6-10membered aromatic ring systems. Phenyl and naphthyl are preferred aryls.The most preferred aryl is phenyl.

The term “heterocyclyl” refers to saturated or unsaturated non-aromaticrings or ring systems containing at least one heteroatom selected fromO, S and N, further including the oxidized forms of sulfur, namely SOand SO₂. Examples of heterocycles include tetrahydrofuran (THF),dihydrofuran, 1,4-dioxane, molpholine, 1,4-dithiane, piperazine,piperidine, 1,3-dioxolane, imidazolidine, imidazoline, pyrroline,pyrrolidine, tetrahydropyran, dihydropyran, oxathiolane, dithiolane,1,3-dioxane, 1,3-dithiane, oxathiane, thiomorpholine, pyrrolidinone,oxazolidin-2-one, imidazolidine-2-one, pyridone, and the like.

“Heteroaryl” means an aromatic or partially aromatic heterocycle thatcontains at least one ring heteroatom selected from O, S and N.Heteroaryls also include heteroaryls fused to other kinds of rings, suchas aryls, cycloalkyls and heterocycles that are not aromatic. Examplesof heteroaryl groups include pyrrolyl, isoxazolyl, isothiazolyl,pyrazolyl, pyridinyl, 2-oxo-(1H)-pyridinyl (2-hydroxy-pyridinyl),oxazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, thiadiazolyl, thiazolyl,imidazolyl, triazolyl, tetrazolyl, furyl, triazinyl, thienyl,pyrimidinyl, pyrazinyl, benzisoxazolyl, benzoxazolyl, benzothiazolyl,benzothiadiazolyl, dihydrobenzofuranyl, indolinyl, pyridazinyl,indazolyl, isoindolyl, dihydrobenzothienyl, indolizinyl, cinnolinyl,phthalazinyl, quinazolinyl, naphthyridinyl, carbazolyl, benzodioxolyl,quinoxalinyl, purinyl, furazanyl, isobenzylfuranyl, benzimidazolyl,benzofuranyl, benzothienyl, quinolyl, indolyl, isoquinolyl,dibenzofuranyl, imidazo[1,2-α]pyridinyl, [1,2,4-triazolo][4,3-a]pyridinyl, pyrazolo[1,5-a]pyridinyl, [1,2,4-triazolo][1,5-a]pyridinyl, 2-oxo-1,3-benzoxazolyl, 4-oxo-3H-quinazolinyl,3-oxo-[1,2,4]-triazolo[4,3-a]-2H-pyridinyl,5-oxo-[1,2,4]-4H-oxadiazolyl, 2-oxo-[1,3,4]-3H-oxadiazolyl,2-oxo-1,3-dihydro-2H-imidazolyl, 3-oxo-2,4-dihydro-3H-1,2,4-triazolyl,and the like. For heterocyclyl and heteroaryl groups, rings and ringsystems containing from 3-15 atoms are included, forming 1-3 rings.

“Halogen” refers to fluorine, chlorine, bromine and iodine. Chlorine andfluorine are generally preferred. Fluorine is most preferred when thehalogens are substituted on an alkyl or alkoxy group (e.g. CF₃O andCF₃CH₂O).

The compounds of the present invention contain one or more asymmetriccenters and can thus occur as racemates, racemic mixtures, singleenantiomers, diastereomeric mixtures, and individual diastereomers. Inparticular the compounds of the present invention have an asymmetriccenter at the stereogenic carbon atoms marked with an * in formulae Ia,Ib, Ic, Id, Ie, and If. Additional asymmetric centers may be presentdepending upon the nature of the various substituents on the molecule.Each such asymmetric center will independently produce two opticalisomers and it is intended that all of the possible optical isomers anddiastereomers in mixtures and as pure or partially purified compoundsare included within the ambit of this invention. The present inventionis meant to comprehend all such isomeric forms of these compounds.

Some of the compounds described herein contain olefinic double bonds,and unless specified otherwise, are meant to include both E and Zgeometric isomers.

Some of the compounds described herein may exist as tautomers, whichhave different points of attachment of hydrogen accompanied by one ormore double bond shifts. For example, a ketone and its enol form areketo-enol tautomers. The individual tautomers as well as mixturesthereof are encompassed with compounds of the present invention.

Formula I shows the structure of the class of compounds withoutpreferred stereochemistry. Formulae Ia and Ib show the preferredstereochemistry at the stereogenic carbon atoms to which are attachedthe NH₂ and Ar groups on the cyclohexane ring. Formulae Ic, Id, Ie, andIf show the preferred stereochemistry at the stereogenic carbon atoms towhich are attached the NH₂, Ar, and N(R⁴)—X—R³ groups on the cyclohexanering.

The independent syntheses of these diastereomers or theirchromatographic separations may be achieved as known in the art byappropriate modification of the methodology disclosed herein. Theirabsolute stereochemistry may be determined by the X-ray crystallographyof crystalline products or crystalline intermediates which arederivatized, if necessary, with a reagent containing an asymmetriccenter of known absolute configuration.

If desired, racemic mixtures of the compounds may be separated so thatthe individual enantiomers are isolated. The separation can be carriedout by methods well known in the art, such as the coupling of a racemicmixture of compounds to an enantiomerically pure compound to form adiastereomeric mixture, followed by separation of the individualdiastereomers by standard methods, such as fractional crystallization orchromatography. The coupling reaction is often the formation of saltsusing an enantiomerically pure acid or base. The diasteromericderivatives may then be converted to the pure enantiomers by cleavage ofthe added chiral residue. The racemic mixture of the compounds can alsobe separated directly by chromatographic methods utilizing chiralstationary phases, which methods are well known in the art.

Alternatively, any enantiomer of a compound may be obtained bystereoselective synthesis using optically pure starting materials orreagents of known configuration by methods well known in the art.

It will be understood that, as used herein, references to the compoundsof structural formula I are meant to also include the pharmaceuticallyacceptable salts, and also salts that are not pharmaceuticallyacceptable when they are used as precursors to the free compounds ortheir pharmaceutically acceptable salts or in other syntheticmanipulations.

The compounds of the present invention may be administered in the formof a pharmaceutically acceptable salt. The term “pharmaceuticallyacceptable salt” refers to salts prepared from pharmaceuticallyacceptable non-toxic bases or acids including inorganic or organic basesand inorganic or organic acids. Salts of basic compounds encompassedwithin the term “pharmaceutically acceptable salt” refer to non-toxicsalts of the compounds of this invention which are generally prepared byreacting the free base with a suitable organic or inorganic acid.Representative salts of basic compounds of the present inventioninclude, but are not limited to, the following: acetate,benzenesulfonate, benzoate, bicarbonate, bisulfate, bitartrate, borate,bromide, camsylate, carbonate, chloride, clavulanate, citrate,dihydrochloride, edetate, edisylate, estolate, esylate, fumarate,gluceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate,hydrabamine, hydrobromide, hydrochloride, hydroxynaphthoate, iodide,isothionate, lactate, lactobionate, laurate, malate, maleate, mandelate,mesylate, methylbromide, methylnitrate, methylsulfate, mucate,napsylate, nitrate, N-methylglucamine ammonium salt, oleate, oxalate,pamoate (embonate), palmitate, pantothenate, phosphate/diphosphate,polygalacturonate, salicylate, stearate, sulfate, subacetate, succinate,tannate, tartrate, teoclate, tosylate, triethiodide and valerate.Furthermore, where the compounds of the invention carry an acidicmoiety, suitable pharmaceutically acceptable salts thereof include, butare not limited to, salts derived from inorganic bases includingaluminum, ammonium, calcium, copper, ferric, ferrous, lithium,magnesium, manganic, mangamous, potassium, sodium, zinc, and the like.Particularly preferred are the ammonium, calcium, magnesium, potassium,and sodium salts. Salts derived from pharmaceutically acceptable organicnon-toxic bases include salts of primary, secondary, and tertiaryamines, cyclic amines, and basic ion-exchange resins, such as arginine,betaine, caffeine, choline, N,N-dibenzylethylenediamine, diethylamine,2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine,ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucamine,glucosamine, histidine, hydrabamine, isopropylamine, lysine,methylglucamine, morpholine, piperazine, piperidine, polyamine resins,procaine, purines, theobromine, triethylamine, trimethylamine,tripropylamine, tromethamine, and the like.

Also, in the case of a carboxylic acid (—COOH) or alcohol group beingpresent in the compounds of the present invention, pharmaceuticallyacceptable esters of carboxylic acid derivatives, such as methyl, ethyl,or pivaloyloxymethyl, or acyl derivatives of alcohols, such as O-acetyl,O-pivaloyl, O-benzoyl, and O-aminoacyl, can be employed. Included arethose esters and acyl groups known in the art for modifying thesolubility or hydrolysis characteristics for use as sustained-release orprodrug formulations.

Solvates, and in particular, the hydrates of the compounds of structuralformula I are included in the present invention as well.

Exemplifying the invention is the use of the compounds disclosed in theExamples and herein.

The subject compounds are useful in a method of inhibiting thedipeptidyl peptidase-IV enzyme in a patient such as a mammal in need ofsuch inhibition comprising the administration of an effective amount ofthe compound. The present invention is directed to the use of thecompounds disclosed herein as inhibitors of dipeptidyl peptidase-IVenzyme activity.

In addition to primates, such as humans, a variety of other mammals canbe treated according to the method of the present invention. Forinstance, mammals including, but not limited to, cows, sheep, goats,horses, dogs, cats, guinea pigs, rats or other bovine, ovine, equine,canine, feline, rodent or murine species can be treated. However, themethod can also be practiced in other species, such as avian species(e.g., chickens).

The present invention is further directed to a method for themanufacture of a medicament for inhibiting dipeptidyl peptidase-IVenzyme activity in humans and animals comprising combining a compound ofthe present invention with a pharmaceutically acceptable carrier ordiluent. More particularly, the present invention is directed to the useof a compound of structural formula I in the manufacture of a medicamentfor use in treating a condition selected from the group consisting ofhyperglycemia, Type 2 diabetes, obesity, and a lipid disorder in amammal, wherein the lipid disorder is selected from the group consistingof dyslipidemia, hyperlipidemia, hypertriglyceridemia,hypercholesterolemia, low HDL, and high LDL.

The subject treated in the present methods is generally a mammal,preferably a human being, male or female, in whom inhibition ofdipeptidyl peptidase-IV enzyme activity is desired. The term“therapeutically effective amount” means the amount of the subjectcompound that will elicit the biological or medical response of atissue, system, animal or human that is being sought by the researcher,veterinarian, medical doctor or other clinician.

The term “composition” as used herein is intended to encompass a productcomprising the specified ingredients in the specified amounts, as wellas any product which results, directly or indirectly, from combinationof the specified ingredients in the specified amounts. Such term inrelation to pharmaceutical composition, is intended to encompass aproduct comprising the active ingredient(s), and the inert ingredient(s)that make up the carrier, as well as any product which results, directlyor indirectly, from combination, complexation or aggregation of any twoor more of the ingredients, or from dissociation of one or more of theingredients, or from other types of reactions or interactions of one ormore of the ingredients. Accordingly, the pharmaceutical compositions ofthe present invention encompass any composition made by admixing acompound of the present invention and a pharmaceutically acceptablecarrier. By “pharmaceutically acceptable” it is meant the carrier,diluent or excipient must be compatible with the other ingredients ofthe formulation and not deleterious to the recipient thereof.

The terms “administration of” and or “administering a” compound shouldbe understood to mean providing a compound of the invention or a prodrugof a compound of the invention to the individual in need of treatment.

The utility of the compounds in accordance with the present invention asinhibitors of dipeptidyl peptidase-IV enzyme activity may bedemonstrated by methodology known in the art. Inhibition constants aredetermined as follows. A continuous fluorometric assay is employed withthe substrate Gly-Pro-AMC, which is cleaved by DPP-IV to release thefluorescent AMC leaving group. The kinetic parameters that describe thisreaction are as follows: K_(m)=50 μM; k_(cat)=75 s⁻¹;k_(cat)/K_(m)=1.5×10⁶ M⁻¹s⁻¹. A typical reaction contains approximately50 pM enzyme, 50 μM Gly-Pro-AMC, and buffer (100 mM HEPES, pH 7.5, 0.1mg/ml BSA) in a total reaction volume of 100 μl. Liberation of AMC ismonitored continuously in a 96-well plate fluorometer using anexcitation wavelength of 360 nm and an emission wavelength of 460 nm.Under these conditions, approximately 0.8 μM AMC is produced in 30minutes at 25 degrees C. The enzyme used in these studies was soluble(transmembrane domain and cytoplasmic extension excluded) human proteinproduced in a baculovirus expression system (Bac-To-Bac, Gibco BRL). Thekinetic constants for hydrolysis of Gly-Pro-AMC and GLP-1 were found tobe in accord with literature values for the native enzyme. To measurethe dissociation constants for compounds, solutions of inhibitor in DMSOwere added to reactions containing enzyme and substrate (final DMSOconcentration is 1%). All experiments were conducted at room temperatureusing the standard reaction conditions described above. To determine thedissociation constants (K_(i)), reaction rates were fit by non-linearregression to the Michaelis-Menton equation for competitive inhibition.The errors in reproducing the dissociation constants are typically lessthan two-fold.

In particular, the compounds of the following examples had activity ininhibiting the dipeptidyl peptidase-IV enzyme in the aforementionedassays, generally with an IC50 of less than about 1 μM. Such a result isindicative of the intrinsic activity of the compounds in use asinhibitors the dipeptidyl peptidase-IV enzyme activity.

Dipeptidyl peptidase-IV enzyme (DPP-IV) is a cell surface protein thathas been implicated in a wide range of biological functions. It has abroad tissue distribution (intestine, kidney, liver, pancreas, placenta,thymus, spleen, epithelial cells, vascular endothelium, lymphoid andmyeloid cells, serum), and distinct tissue and cell-type expressionlevels. DPP-IV is identical to the T cell activation marker CD26, and itcan cleave a number of immunoregulatory, endocrine, and neurologicalpeptides in vitro. This has suggested a potential role for thispeptidase in a variety of disease processes in humans or other species.

Accordingly, the subject compounds are useful in a method for theprevention or treatment of the following diseases, disorders andconditions.

Type II Diabetes and Related Disorders: It is well established that theincretins GLP-1 and GIP are rapidly inactivated in vivo by DPP-IV.Studies with DPP-IV^((−/−))-deficient mice and preliminary clinicaltrials indicate that DPP-IV inhibition increases the steady stateconcentrations of GLP-1 and GIP, resulting in improved glucosetolerance. By analogy to GLP-1 and GIP, it is likely that other glucagonfamily peptides involved in glucose regulation are also inactivated byDPP-IV (eg. PACAP). Inactivation of these peptides by DPP-IV may alsoplay a role in glucose homeostasis. The DPP-IV inhibitors of the presentinvention therefore have utility in the treatment of type II diabetesand in the treatment and prevention of the numerous conditions thatoften accompany Type II diabetes, including Syndrome X (also known asMetabolic Syndrome), reactive hypoglycemia, and diabetic dyslipidemia.Obesity, discussed below, is another condition that is often found withType II diabetes that may respond to treatment with the compounds ofthis invention.

The following diseases, disorders and conditions are related to Type 2diabetes, and therefore may be treated, controlled or in some casesprevented, by treatment with the compounds of this invention: (1)hyperglycemia, (2) low glucose tolerance, (3) insulin resistance, (4)obesity, (5) lipid disorders, (6) dyslipidemia, (7) hyperlipidemia, (8)hypertriglyceridemia, (9) hypercholesterolemia, (10) low HDL levels,(11) high LDL levels, (12) atherosclerosis and its sequelae, (13)vascular restenosis, (14) irritable bowel syndrome, (15) inflammatorybowel disease, including Crohn's disease and ulcerative colitis, (16)other inflammatory conditions, (17) pancreatitis, (18) abdominalobesity, (19) neurodegenerative disease, (20) retinopathy, (21)nephropathy, (22) neuropathy, (23) Syndrome X, (24) ovarianhyperandrogenism (polycystic ovarian syndrome), and other disorderswhere insulin resistance is a component. In Syndrome X, also known asMetabolic Syndrome, obesity is thought to promote insulin resistance,diabetes, dyslipidemia, hypertension, and increased cardiovascular risk.Therefore, DPP-IV inhibitors may also be useful to treat hypertensionassociated with this condition.

Obesity: DPP-IV inhibitors may be useful for the treatment of obesity.This is based on the observed inhibitory effects on food intake andgastric emptying of GLP-1 and GLP-2. Exogenous administration of GLP-1in humans significantly decreases food intake and slows gastric emptying(Am. J. Physiol., 277: R910-R916 (1999)). ICV administration of GLP-1 inrats and mice also has profound effects on food intake (Nature Medicine2: 1254-1258 (1996)). This inhibition of feeding is not observed inGLP-1R^((−/−)) mice, indicating that these effects are mediated throughbrain GLP-1 receptors. By analogy to GLP-1, it is likely that GLP-2 isalso regulated by DPP-IV. ICV administration of GLP-2 also inhibits foodintake, analogous to the effects observed with GLP-1 (Nature Medicine,6: 802-807 (2000)). In addition, studies with DPP-IV deficient micesuggest that these animals are resistant to diet-induced obesity andassociated pathology (e.g. hyperinsulinonemia). Cardiovascular Disease:GLP-1 has been shown to be beneficial when administered to patientsfollowing acute myocardial infarction, leading to improved leftventricular function and reduced mortality after primary angioplasty(Circulation, 109: 962-965 (2004)). GLP-1 administration is also usefulfor the treatment of left ventricular systolic dysfunction in dogs withdilated cardiomyopathy and ischemic induced left ventriculardysfunction, and thus may prove useful for the treatment of patientswith heart failure (US2004/009741 1). DPP-IV inhibitors are expected toshow similar effects through their ability to stabilize endogenousGLP-1.

Growth Hormone Deficiency: DPP-IV inhibition may be useful for thetreatment of growth hormone deficiency, based on the hypothesis thatgrowth-hormone releasing factor (GRF), a peptide that stimulates releaseof growth hormone from the anterior pituitary, is cleaved by the DPP-IVenzyme in vivo (WO 00/56297). The following data provide evidence thatGRF is an endogenous substrate: (1) GRF is efficiently cleaved in vitroto generate the inactive product GRF[3-44] (BBA 1122: 147-153 (1992));(2) GRF is rapidly degraded in plasma to GRF[3-44]; this is prevented bythe DPP-IV inhibitor diprotin A; and (3) GRF[3-44] is found in theplasma of a human GRF transgenic pig (J. Clin. Invest., 83: 1533-1540(1989)). Thus DPP-IV inhibitors may be useful for the same spectrum ofindications which have been considered for growth hormone secretagogues.

Intestinal Injury: The potential for using DPP-IV inhibitors for thetreatment of intestinal injury is suggested by the results of studiesindicating that glucagon-like peptide-2 (GLP-2), a likely endogenoussubstrate for DPP-IV, may exhibit trophic effects on the intestinalepithelium (Regulatory Peptides. 90: 27-32 (2000)). Administration ofGLP-2 results in increased small bowel mass in rodents and attenuatesintestinal injury in rodent models of colitis and enteritis.

Imunosuppression: DPP-IV inhibition may be useful for modulation of theimmune response, based upon studies implicating the DPP-IV enzyme in Tcell activation and in chemokine processing, and efficacy of DPP-IVinhibitors in in vivo models of disease. DPP-IV has been shown to beidentical to CD26, a cell surface marker for activated immune cells. Theexpression of CD26 is regulated by the differentiation and activationstatus of immune cells. It is generally accepted that CD26 functions asa co-stimulatory molecule in in vitro models of T cell activation. Anumber of chemokines contain proline in the penultimate position,presumably to protect them from degradation by non-specificaminopeptidases. Many of these have been shown to be processed in vitroby DPP-IV. In several cases (RANTES, LD78-beta, MDC, eotaxin,SDF-lalpha), cleavage results in an altered activity in chemotaxis andsignaling assays. Receptor selectivity also appears to be modified insome cases (RANTES). Multiple N-terminally truncated forms of a numberof chemokines have been identified in in vitro cell culture systems,including the predicted products of DPP-IV hydrolysis.

DPP-IV inhibitors have been shown to be efficacious immunosuppressantsin animal models of transplantation and arthritis. Prodipine(Pro-Pro-diphenyl-phosphonate), an irreversible inhibitor of DPP-IV, wasshown to double cardiac allograft survival in rats from day 7 to day 14(Transplantation. 63: 1495-1500 (1997)). DPP-IV inhibitors have beentested in collagen and alkyldiamine-induced arthritis in rats and showeda statistically significant attenuation of hind paw swelling in thismodel [Int. J. Immunopharmacology, 19:15-24 (1997) andImmunopharmacology, 40: 21-26 (1998)]. DPP-IV is upregulated in a numberof autoimmune diseases including rheumatoid arthritis, multiplesclerosis, Graves' disease, and Hashimoto's thyroiditis (ImmunologyToday. 20: 367-375 (1999)).

HIV Infection: DPP-IV inhibition may be useful for the treatment orprevention of HIV infection or AIDS because a number of chemokines whichinhibit HIV cell entry are potential substrates for DPP-IV (ImmunologyToday 20: 367-375 (1999)). In the case of SDF-lalpha, cleavage decreasesantiviral activity (PNAS, 95: 6331-6 (1998)). Thus, stabilization ofSDF-lalpha through inhibition of DPP-IV would be expected to decreaseHIV infectivity.

Hematopoiesis: DPP-IV inhibition may be useful for the treatment orprevention of hematopiesis because DPP-IV may be involved inhematopoiesis. A DPP-IV inhibitor, Val-Boro-Pro, stimulatedhematopoiesis in a mouse model of cyclophosphamide-induced neutropenia(WO 99/56753).

Neuronal Disorders: DPP-IV inhibition may be useful for the treatment orprevention of various neuronal or psychiatric disorders because a numberof peptides implicated in a variety of neuronal processes are cleaved invitro by DPP-IV. A DPP-IV inhibitor thus may have a therapeutic benefitin the treatment of neuronal disorders. Endomorphin-2, beta-casomorphin,and substance P have all been shown to be in vitro substrates forDPP-IV. In all cases, in vitro cleavage is highly efficient, withk_(cat)/K_(m) about 10⁶ M⁻¹s⁻¹ or greater. In an electric shock jumptest model of analgesia in rats, a DPP-IV inhibitor showed a significanteffect that was independent of the presence of exogenous endomorphin-2(Brain Research, 815: 278-286 (1999)). Neuroprotective andneuroregenerative effects of DPP-IV inhibitors were also evidenced bythe inhibitors' ability to protect motor neurons from excitotoxic celldeath, to protect striatal innervation of dopaminergic neurons whenadministered concurrently with MPTP, and to promote recovery of striatalinnervation density when given in a therapeutic manner following MPTPtreatment [see Yong-Q. Wu, et al., “Neuroprotective Effects ofInhibitors of Dipeptidyl Peptidase-IV In Vitro and In Vivo,” Int. Conf.On Dipeptidyl Aminopeptidases: Basic Science and Clinical Applications,Sep. 26-29, 2002 (Berlin, Germany)].

Anxiety: Rats naturally deficient in DPP-IV have an anxiolytic phenotype(WO 02/34243; Karl et al.,

Physiol. Behav. 2003). DPP-IV deficient mice also have an anxiolyticphenotype using the porsolt and light/dark models. Thus DPP-IVinhibitors may prove useful for treating anxiety and related disorders.

Memory and Cognition: GLP-1 agonists are active in models of learning(passive avoidance, Morris water maze) and neuronal injury(kainate-induced neuronal apoptosis) as demonstrated by During et al.

(Nature Med. 9: 1173-1179 (2003)). The results suggest a physiologicalrole for GLP-1 in learning and neuroprotection. Stabilization of GLP-1by DPP-IV inhibitors are expected to show similar effects

Myocardial Infarction: GLP-1 has been shown to be beneficial whenadministered to patients following acute myocardial infarction(Circulation, 109: 962-965 (2004)). DPP-IV inhibitors are expected toshow similar effects through their ability to stabilize endogenousGLP-1.

Tumor Invasion and Metastasis: DPP-IV inhibition may be useful for thetreatment or prevention of tumor invasion and metastasis because anincrease or decrease in expression of several ectopeptidases includingDPP-IV has been observed during the transformation of normal cells to amalignant phenotype

(J. Exp. Med., 190: 301-305 (1999)). Up- or down-regulation of theseproteins appears to be tissue and cell-type specific. For example,increased CD26/DPP-IV expression has been observed on T cell lymphoma, Tcell acute lymphoblastic leukemia, cell-derived thyroid carcinomas,basal cell carcinomas, and breast carcinomas. Thus, DPP-IV inhibitorsmay have utility in the treatment of such carcinomas.

Benign Prostatic Hypertrophy: DPP-IV inhibition may be useful for thetreatment of benign prostatic hypertrophy because increased DPP-IVactivity was noted in prostate tissue from patients with BPH

(Eur. J. Clin. Chem. Clin. Biochem. 30: 333-338 (1992)).

Sperm motility/male contraception: DPP-IV inhibition may be useful forthe altering sperm motility and for male contraception because inseminal fluid, prostatosomes, prostate derived organelles important forsperm motility, possess very high levels of DPP-IV activity (Eur. J.Clin. Chem. Clin. Biochem., 30: 333-338 (1992)).

Gingivitis: DPP-IV inhibition may be useful for the treatment ofgingivitis because DPP-IV activity was found in gingival crevicularfluid and in some studies correlated with periodontal disease severity(Arch. Oral Biol., 37: 167-173 (1992)).

Osteoporosis: DPP-IV inhibition may be useful for the treatment orprevention of osteoporosis because GIP receptors are present inosteoblasts.

Stem Cell Transplantation: Inhibition of DPP-IV on donor stem cells hasbeen shown to lead to an enhancement of their bone marrow homingefficiency and engraftment, and an increase in survival in mice(Christopherson, et al., Science, 305:1000-1003 (2004)). Thus DPP-IVinhibitors may be useful in bone marrow transplantation.

The compounds of the present invention have utility in treating orpreventing one or more of the following conditions or diseases: (1)hyperglycemia, (2) low glucose tolerance, (3) insulin resistance, (4)obesity, (5) lipid disorders, (6) dyslipidemia, (7) hyperlipidemia, (8)hypertriglyceridemia, (9) hypercholesterolemia, (10) low HDL levels,(11) high LDL levels, (12) atherosclerosis and its sequelae, (13)vascular restenosis, (14) irritable bowel syndrome, (15) inflammatorybowel disease, including Crohn's disease and ulcerative colitis, (16)other inflammatory conditions, (17) pancreatitis, (18) abdominalobesity, (19) neurodegenerative disease, (20) retinopathy, (21)nephropathy, (22) neuropathy, (23) Syndrome X, (24) ovarianhyperandrogenism (polycystic ovarian syndrome), (25) Type 2 diabetes,(26) growth hormone deficiency, (27) neutropenia, (28) neuronaldisorders, (29) tumor metastasis, (30) benign prostatic hypertrophy,(32) gingivitis, (33) hypertension, (34) osteoporosis, and otherconditions that may be treated or prevented by inhibition of DPP-IV.

The subject compounds are further useful in a method for the preventionor treatment of the aforementioned diseases, disorders and conditions incombination with other agents.

The compounds of the present invention may be used in combination withone or more other drugs in the treatment, prevention, suppression oramelioration of diseases or conditions for which compounds of Formula Ior the other drugs may have utility, where the combination of the drugstogether are safer or more effective than either drug alone. Such otherdrug(s) may be administered, by a route and in an amount commonly usedtherefor, contemporaneously or sequentially with a compound of FormulaI. When a compound of Formula I is used contemporaneously with one ormore other drugs, a pharmaceutical composition in unit dosage formcontaining such other drugs and the compound of Formula I is preferred.However, the combination therapy may also include therapies in which thecompound of Formula I and one or more other drugs are administered ondifferent overlapping schedules. It is also contemplated that when usedin combination with one or more other active ingredients, the compoundsof the present invention and the other active ingredients may be used inlower doses than when each is used singly. Accordingly, thepharmaceutical compositions of the present invention include those thatcontain one or more other active ingredients, in addition to a compoundof Formula I.

Examples of other active ingredients that may be administered incombination with a compound of Formula I, and either administeredseparately or in the same pharmaceutical composition, include, but arenot limited to:

(a) other dipeptidyl peptidase IV (DPP-IV) inhibitors;

(b) insulin sensitizers including (i) PPARγ agonists, such as theglitazones (e.g. troglitazone, pioglitazone, englitazone, MCC-555,rosiglitazone, balaglitazone, and the like) and other PPAR ligands,including PPARα/γ dual agonists, such as KRP-297, muraglitazar,naveglitazar, tesaglitazar, TAK-559, PPARα agonists, such as fenofibricacid derivatives (gemfibrozil, clofibrate, fenofibrate and bezafibrate),and selective PPARγ modulators (SPPARγM's), such as disclosed in WO02/060388, WO 02/08188, WO 2004/019869, WO 2004/020409, WO 2004/020408,and WO 2004/066963; (ii) biguanides such as metformin and phenformin,and (iii) protein tyrosine phosphatase-1B (PTP-1B) inhibitors;

(c) insulin or insulin mimetics;

(d) sulfonylureas and other insulin secretagogues, such as tolbutamide,glyburide, glipizide, glimepiride, and meglitinides, such as nateglinideand repaglinide;

(e) α-glucosidase inhibitors (such as acarbose and miglitol);

(f) glucagon receptor antagonists, such as those disclosed in WO97/16442; WO 98/04528, WO 98/21957; WO 98/22108; WO 98/22109; WO99/01423, WO 00/39088, and WO 00/69810; WO 2004/050039; and WO2004/069158;

(g) GLP-1, GLP-1 analogues or mimetics, and GLP-1 receptor agonists,such as exendin-4 (exenatide), liraglutide (NN-2211), CJC-1131,LY-307161, and those disclosed in WO 00/42026 and WO 00/59887;

(h) GIP and GIP mimetics, such as those disclosed in WO 00/58360, andGIP receptor agonists;

(i) PACAP, PACAP mimetics, and PACAP receptor agonists such as thosedisclosed in WO 01/23420;

(j) cholesterol lowering agents such as (i) HMG-CoA reductase inhibitors(lovastatin, simvastatin, pravastatin, cerivastatin, fluvastatin,atorvastatin, itavastatin, and rosuvastatin, and other statins), (ii)sequestrants (cholestyramine, colestipol, and dialkylaminoalkylderivatives of a cross-linked dextran), (iii) nicotinyl alcohol,nicotinic acid or a salt thereof, (iv) PPARα agonists such as fenofibricacid derivatives (gemfibrozil, clofibrate, fenofibrate and bezafibrate),(v) PPARα/γ dual agonists, such as naveglitazar and muraglitazar, (vi)inhibitors of cholesterol absorption, such as beta-sitosterol andezetimibe, (vii) acyl CoA:cholesterol acyltransferase inhibitors, suchas avasimibe, and (viii) antioxidants, such as probucol;

(k) PPARδ agonists, such as those disclosed in WO 97/28149;

(l) antiobesity compounds, such as fenfluramine, dexfenfluramine,phentermine, sibutramine, orlistat, neuropeptide Y₁ or Y₅ antagonists,CB 1 receptor inverse agonists and antagonists, β₃ adrenergic receptoragonists, melanocortin-receptor agonists, in particular melanocortin-4receptor agonists, ghrelin antagonists, bombesin receptor agonists (suchas bombesin receptor subtype-3 agonists), and melanin-concentratinghormone (MCH) receptor antagonists;

(m) ileal bile acid transporter inhibitors;

(n) agents intended for use in inflammatory conditions such as aspirin,non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids,azulfidine, and selective cyclooxygenase-2 (COX-2) inhibitors;

(o) antihypertensive agents, such as ACE inhibitors (enalapril,lisinopril, captopril, quinapril, tandolapril), A-II receptor blockers(losartan, candesartan, irbesartan, valsartan, telmisartan, andeprosartan), beta blockers and calcium channel blockers;

(p) glucokinase activators (GKAs), such as those disclosed in WO03/015774; WO 04/076420; and WO 04/081001;

(q) inhibitors of 11β-hydroxysteroid dehydrogenase type 1, such as thosedisclosed in U.S. Pat. No. 6,730,690; WO 03/104207; and WO 04/058741;

(r) inhibitors of cholesteryl ester transfer protein (CETP), such astorcetrapib; and

(s) inhibitors of fructose 1,6-bisphosphatase, such as those disclosedin U.S. Pat. Nos. 6,054,587; 6,110,903; 6,284,748; 6,399,782; and6,489,476.

Dipeptidyl peptidase-IV inhibitors that can be combined with compoundsof structural formula I include those disclosed in U.S. Pat. No.6,699,871; WO 02/076450 (3 Oct. 2002); WO 03/004498 (16 Jan. 2003); WO03/004496 (16 Jan. 2003); EP 1 258 476 (20 Nov. 2002); WO 02/083128 (24Oct. 2002); WO 02/062764 (15 Aug. 2002); WO 03/000250 (3 Jan. 2003); WO03/002530 (9 Jan. 2003); WO 03/002531 (9 Jan. 2003); WO 03/002553 (9Jan. 2003); WO 03/002593 (9 Jan. 2003); WO 03/000180 (3 Jan. 2003); WO03/082817 (9 Oct. 2003); WO 03/000181 (3 Jan. 2003); WO 04/007468 (22Jan. 2004); WO 04/032836 (24 Apr. 2004); WO 04/037169 (6 May 2004); andWO 04/043940 (27 May 2004). Specific DPP-IV inhibitor compounds includeisoleucine thiazolidide (P32/98); NVP-DPP-728; vildagliptin (LAF 237);P93/01; and saxagliptin (BMS 477118).

Antiobesity compounds that can be combined with compounds of structuralformula I include fenfluramine, dexfenfluramine, phentermine,sibutramine, orlistat, neuropeptide Y₁ or Y₅ antagonists, cannabinoid CB1 receptor antagonists or inverse agonists, melanocortin receptoragonists, in particular, melanocortin-4 receptor agonists, ghrelinantagonists, bombesin receptor agonists, and melanin-concentratinghormone (MCH) receptor antagonists. For a review of anti-obesitycompounds that can be combined with compounds of structural formula I,see S. Chaki et al., “Recent advances in feeding suppressing agents:potential therapeutic strategy for the treatment of obesity,” ExpertOpin. Ther. Patents, 11: 1677-1692 (2001); D. Spanswick and K. Lee,“Emerging antiobesity drugs,” Expert Opin. Emerging Drugs, 8: 217-237(2003); and J. A. Fernandez-Lopez, et al., “Pharmacological Approachesfor the Treatment of Obesity,” Drugs, 62: 915-944 (2002).

Neuropeptide Y5 antagonists that can be combined with compounds ofstructural formula I include those disclosed in U.S. Pat. No. 6,335,345(1 Jan. 2002) and WO 01/14376 (1 Mar. 2001); and specific compoundsidentified as GW 59884A; GW 569180A; LY366377; and CGP-71683A.

Cannabinoid CB 1 receptor antagonists that can be combined withcompounds of formula I include those disclosed in PCT Publication WO03/007887; U.S. Pat. No. 5,624,941, such as rimonabant; PCT PublicationWO 02/076949, such as SLV-319; U.S. Pat. No. 6,028,084; PCT PublicationWO 98/41519; PCT Publication WO 00/10968; PCT Publication WO 99/02499;U.S. Pat. No. 5,532,237; U.S. Pat. No. 5,292,736; PCT Publication WO03/086288; PCT Publication WO 03/087037; PCT Publication WO 04/048317;PCT Publication WO 03/007887; PCT Publication WO 03/063781; PCTPublication WO 03/075660; PCT Publication WO 03/077847; PCT PublicationWO 03/082190; PCT Publication WO 03/082191; PCT Publication WO03/087037; PCT Publication WO 03/086288; PCT Publication WO 04/012671;PCT Publication WO 04/029204; PCT Publication WO 04/040040; PCTPublication WO 01/64632; PCT Publication WO 01/64633; and PCTPublication WO 01/64634.

Melanocortin-4 receptor (MC4R) agonists useful in the present inventioninclude, but are not limited to, those disclosed in U.S. Pat. No.6,294,534, U.S. Pat. Nos. 6,350,760, 6,376,509, 6,410,548, 6,458,790,U.S. Pat. No. 6,472,398, U.S. Pat. No. 5,837,521, U.S. Pat. No.6,699,873, which are hereby incorporated by reference in their entirety;in US Patent Application Publication Nos. US 2002/0004512,US2002/0019523, US2002/0137664, US2003/0236262, US2003/0225060,US2003/0092732, US2003/109556, US 2002/0177151, US 2002/187932, US2003/0113263, which are hereby incorporated by reference in theirentirety; and in WO 99/64002, WO 00/74679, WO 02/15909, WO 01/70708, WO01/70337, WO 01/91752, WO 02/068387, WO 02/068388, WO 02/067869, WO03/007949, WO 2004/024720, WO 2004/089307, WO 2004/078716, WO2004/078717, WO 2004/037797, WO 01/58891, WO 02/070511, WO 02/079146, WO03/009847, WO 03/057671, WO 03/068738, WO 03/092690, WO 02/059095, WO02/059107, WO 02/059108, WO 02/059117, WO 02/085925, WO 03/004480, WO03/009850, WO 03/013571, WO 03/031410, WO 03/053927, WO 03/061660, WO03/066597, WO 03/094918, WO 03/099818, WO 04/037797, WO 04/048345, WO02/018327, WO 02/080896, WO 02/081443, WO003/066587, WO 03/066597, WO03/099818, WO 02/062766, WO 03/000663, WO 03/000666, WO 03/003977, WO03/040107, WO 03/040117, WO 03/040118, WO 03/013509, WO 03/057671, WO02/079753, WO 02//092566, WO 03/-093234, WO 03/095474, and WO 03/104761.

The potential utility of safe and effective activators of glucokinase(GKAs) for the treatment of diabetes is discussed in J. Grimsby et al.,“Allosteric Activators of Glucokinase: Potential Role in DiabetesTherapy,” Science, 301: 370-373 (2003).

When a compound of the present invention is used contemporaneously withone or more other drugs, a pharmaceutical composition containing suchother drugs in addition to the compound of the present invention ispreferred. Accordingly, the pharmaceutical compositions of the presentinvention include those that also contain one or more other activeingredients, in addition to a compound of the present invention.

The weight ratio of the compound of the present invention to the secondactive ingredient may be varied and will depend upon the effective doseof each ingredient. Generally, an effective dose of each will be used.Thus, for example, when a compound of the present invention is combinedwith another agent, the weight ratio of the compound of the presentinvention to the other agent will generally range from about 1000:1 toabout 1:1000, preferably about 200:1 to about 1:200. Combinations of acompound of the present invention and other active ingredients willgenerally also be within the aforementioned range, but in each case, aneffective dose of each active ingredient should be used.

In such combinations the compound of the present invention and otheractive agents may be administered separately or in conjunction. Inaddition, the administration of one element may be prior to, concurrentto, or subsequent to the administration of other agent(s).

The compounds of the present invention may be administered by oral,parenteral (e.g., intramuscular, intraperitoneal, intravenous, ICV,intracisternal injection or infusion, subcutaneous injection, orimplant), by inhalation spray, nasal, vaginal, rectal, sublingual, ortopical routes of administration and may be formulated, alone ortogether, in suitable dosage unit formulations containing conventionalnon-toxic pharmaceutically acceptable carriers, adjuvants and vehiclesappropriate for each route of administration. In addition to thetreatment of warm-blooded animals such as mice, rats, horses, cattle,sheep, dogs, cats, monkeys, etc., the compounds of the invention areeffective for use in humans.

The pharmaceutical compositions for the administration of the compoundsof this invention may conveniently be presented in dosage unit form andmay be prepared by any of the methods well known in the art of pharmacy.All methods include the step of bringing the active ingredient intoassociation with the carrier which constitutes one or more accessoryingredients. In general, the pharmaceutical compositions are prepared byuniformly and intimately bringing the active ingredient into associationwith a liquid carrier or a finely divided solid carrier or both, andthen, if necessary, shaping the product into the desired formulation. Inthe pharmaceutical composition the active object compound is included inan amount sufficient to produce the desired effect upon the process orcondition of diseases. As used herein, the term “composition” isintended to encompass a product comprising the specified ingredients inthe specified amounts, as well as any product which results, directly orindirectly, from combination of the specified ingredients in thespecified amounts.

The pharmaceutical compositions containing the active ingredient may bein a form suitable for oral use, for example, as tablets, troches,lozenges, aqueous or oily suspensions, dispersible powders or granules,emulsions, hard or soft capsules, or syrups or elixirs. Compositionsintended for oral use may be prepared according to any method known tothe art for the manufacture of pharmaceutical compositions and suchcompositions may contain one or more agents selected from the groupconsisting of sweetening agents, flavoring agents, coloring agents andpreserving agents in order to provide pharmaceutically elegant andpalatable preparations. Tablets contain the active ingredient inadmixture with non-toxic pharmaceutically acceptable excipients whichare suitable for the manufacture of tablets. These excipients may be forexample, inert diluents, such as calcium carbonate, sodium carbonate,lactose, calcium phosphate or sodium phosphate; granulating anddisintegrating agents, for example, corn starch, or alginic acid;binding agents, for example starch, gelatin or acacia, and lubricatingagents, for example magnesium stearate, stearic acid or talc. Thetablets may be uncoated or they may be coated by known techniques todelay disintegration and absorption in the gastrointestinal tract andthereby provide a sustained action over a longer period. For example, atime delay material such as glyceryl monostearate or glyceryl distearatemay be employed. They may also be coated by the techniques described inthe U.S. Pat. Nos. 4,256,108; 4,166,452; and 4,265,874 to form osmotictherapeutic tablets for control release.

Formulations for oral use may also be presented as hard gelatin capsuleswherein the active ingredient is mixed with an inert solid diluent, forexample, calcium carbonate, calcium phosphate or kaolin, or as softgelatin capsules wherein the active ingredient is mixed with water or anoil medium, for example peanut oil, liquid paraffin, or olive oil.

Aqueous suspensions contain the active materials in admixture withexcipients suitable for the manufacture of aqueous suspensions. Suchexcipients are suspending agents, for example sodiumcarboxymethylcellulose, methylcellulose, hydroxy-propylmethylcellulose,sodium alginate, polyvinyl-pyrrolidone, gum tragacanth and gum acacia;dispersing or wetting agents may be a naturally-occurring phosphatide,for example lecithin, or condensation products of an alkylene oxide withfatty acids, for example polyoxyethylene stearate, or condensationproducts of ethylene oxide with long chain aliphatic alcohols, forexample heptadecaethyleneoxycetanol, or condensation products ofethylene oxide with partial esters derived from fatty acids and ahexitol such as polyoxyethylene sorbitol monooleate, or condensationproducts of ethylene oxide with partial esters derived from fatty acidsand hexitol anhydrides, for example polyethylene sorbitan monooleate.The aqueous suspensions may also contain one or more preservatives, forexample ethyl or n-propyl p-hydroxybenzoate, one or more coloringagents, one or more flavoring agents, and one or more sweetening agents,such as sucrose or saccharin.

Oily suspensions may be formulated by suspending the active ingredientin a vegetable oil, for example arachis oil, olive oil, sesame oil orcoconut oil, or in a mineral oil such as liquid paraffin. The oilysuspensions may contain a thickening agent, for example beeswax, hardparaffin or cetyl alcohol. Sweetening agents such as those set forthabove, and flavoring agents may be added to provide a palatable oralpreparation. These compositions may be preserved by the addition of ananti-oxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueoussuspension by the addition of water provide the active ingredient inadmixture with a dispersing or wetting agent, suspending agent and oneor more preservatives. Suitable dispersing or wetting agents andsuspending agents are exemplified by those already mentioned above.Additional excipients, for example sweetening, flavoring and coloringagents, may also be present.

The pharmaceutical compositions of the invention may also be in the formof oil-in-water emulsions. The oily phase may be a vegetable oil, forexample olive oil or arachis oil, or a mineral oil, for example liquidparaffin or mixtures of these. Suitable emulsifying agents may benaturally-occurring gums, for example gum acacia or gum tragacanth,naturally-occurring phosphatides, for example soy bean, lecithin, andesters or partial esters derived from fatty acids and hexitolanhydrides, for example sorbitan monooleate, and condensation productsof the said partial esters with ethylene oxide, for examplepolyoxyethylene sorbitan monooleate. The emulsions may also containsweetening and flavoring agents.

Syrups and elixirs may be formulated with sweetening agents, for exampleglycerol, propylene glycol, sorbitol or sucrose. Such formulations mayalso contain a demulcent, a preservative and flavoring and coloringagents.

The pharmaceutical compositions may be in the form of a sterileinjectable aqueous or oleagenous suspension. This suspension may beformulated according to the known art using those suitable dispersing orwetting agents and suspending agents which have been mentioned above.The sterile injectable preparation may also be a sterile injectablesolution or suspension in a non-toxic parenterally-acceptable diluent orsolvent, for example as a solution in 1,3-butane diol. Among theacceptable vehicles and solvents that may be employed are water,Ringer's solution and isotonic sodium chloride solution. In addition,sterile, fixed oils are conventionally employed as a solvent orsuspending medium. For this purpose any bland fixed oil may be employedincluding synthetic mono- or diglycerides. In addition, fatty acids suchas oleic acid find use in the preparation of injectables.

The compounds of the present invention may also be administered in theform of suppositories for rectal administration of the drug. Thesecompositions can be prepared by mixing the drug with a suitablenon-irritating excipient which is solid at ordinary temperatures butliquid at the rectal temperature and will therefore melt in the rectumto release the drug. Such materials are cocoa butter and polyethyleneglycols.

For topical use, creams, ointments, jellies, solutions or suspensions,etc., containing the compounds of the present invention are employed.(For purposes of this application, topical application shall includemouthwashes and gargles.) The pharmaceutical composition and method ofthe present invention may further comprise other therapeutically activecompounds as noted herein which are usually applied in the treatment ofthe above mentioned pathological conditions.

In the treatment or prevention of conditions which require inhibition ofdipeptidyl peptidase-IV enzyme activity an appropriate dosage level willgenerally be about 0.01 to 500 mg per kg patient body weight per daywhich can be administered in single or multiple doses. Preferably, thedosage level will be about 0.1 to about 250 mg/kg per day; morepreferably about 0.5 to about 100 mg/kg per day. A suitable dosage levelmay be about 0.01 to 250 mg/kg per day, about 0.05 to 100 mg/kg per day,or about 0.1 to 50 mg/kg per day. Within this range the dosage may be0.05 to 0.5, 0.5 to 5 or 5 to 50 mg/kg per day. For oral administration,the compositions are preferably provided in the form of tabletscontaining 1.0 to 1000 mg of the active ingredient, particularly 1.0,5.0, 10.0, 15.0. 20.0, 25.0, 50.0, 75.0, 100.0, 150.0, 200.0, 250.0,300.0, 400.0, 500.0, 600.0, 750.0, 800.0, 900.0, and 1000.0 mg of theactive ingredient for the symptomatic adjustment of the dosage to thepatient to be treated. The compounds may be administered on a regimen of1 to 4 times per day, preferably once or twice per day.

When treating or preventing diabetes mellitus and/or hyperglycemia orhypertriglyceridemia or other diseases for which compounds of thepresent invention are indicated, generally satisfactory results areobtained when the compounds of the present invention are administered ata daily dosage of from about 0.1 mg to about 100 mg per kilogram ofanimal body weight, preferably given as a single daily dose or individed doses two to six times a day, or in sustained release form. Formost large mammals, the total daily dosage is from about 1.0 mg to about1000 mg, preferably from about 1 mg to about 50 mg. In the case of a 70kg adult human, the total daily dose will generally be from about 7 mgto about 350 mg. This dosage regimen may be adjusted to provide theoptimal therapeutic response.

It will be understood, however, that the specific dose level andfrequency of dosage for any particular patient may be varied and willdepend upon a variety of factors including the activity of the specificcompound employed, the metabolic stability and length of action of thatcompound, the age, body weight, general health, sex, diet, mode and timeof administration, rate of excretion, drug combination, the severity ofthe particular condition, and the host undergoing therapy.

Synthetic methods for preparing the compounds of the present inventionare illustrated in the following Schemes and Examples. Startingmaterials are commercially available or may be made according toprocedures known in the art or as illustrated herein.

The compounds of the present invention can be prepared fromintermediates such as those of formula II and III using standardreductive amination conditions followed by deprotection. The preparationof these intermediates is described in the following Schemes,

wherein Ar, R³ and R⁴ are as defined above, X is a bond, and P is asuitable nitrogen protecting group such as tert-butoxycarbonyl (BOC),benzyloxycarbonyl (Cbz), and 9-fluorenylmethoxycarbonyl (Fmoc).

Compounds of formula II are known in the literature or may beconveniently prepared by a variety of methods familiar to those skilledin the art. One common route is illustrated in Scheme 1. Bromo or iodosubstituted benzene 1 is treated with magnesium to form thecorresponding Grignard reagent or lithiated with reagents such asn-butyllithium and then treated with cyclohexanone 2 to form thetertiary alcohol 3. Alcohol 3 is dehydrated, for example, by treatmentwith phosphorus oxychloride or by treatment with p-toluenesulfonic acidin toluene with azeotropic removal of water, to provide styrene 4.Reduction by treatment with hydrogen in the presence of a catalyst suchas palladium on carbon yields the protected 4-aryl substitutedcyclohexanone 5. Deprotection under acidic conditions gives thecyclohexanone 6, which is then converted to a silyl enol ether, such astriisopropylsilyl enol ether 7 using reagents and methods familiar tothose skilled in the art. The enol ether 7 upon treatment withiodosobenzene and trimethylsilyl azide forms the azido cycohexene 8,which upon reduction to the amine with lithium aluminum hydride or otherreducing agents known in the literature yields the amine 9, as a mixtureof cis and trans isomers. Protection of the resulting amine, forexample, as its BOC derivative by treatment with di-tert-butyldicarbonate, gives 10. Treatment of 10 with a source of fluoride anionremoves the silyl protecting group and gives Intermediate IIa.

An alternative method to prepare Intermediate II is shown in Scheme 2.The commercially available ketone 2 is treated with dimethyl carbonateto form the keto ester 11, which is then transformed to the enoltriflate 12 upon treatment with trifluoromethanesulfonic anhydride.Treatment of 12 with aryl boronic acid 13 gives the aryl cycohexene 14.Reduction of 14 is readily achieved with reagents such Mg in methanol toprovide ester 15 as a mixture of cis and trans isomers. Conversion tothe thermodynamically more stable traits isomer 16 is effected bytreatment with a base such as sodium methoxide in solvent such asmethanol. Hydrolysis of the ester with a base such as lithium hydroxideto form the acid 17 followed by Curtius rearrangement gives the amine18, as its benzyl carbamate derivative. Deprotection of the ketal bytreatment with acid such as p-toluenesulfonic acid in dioxane providesIntermediate IIb.

An alternative approach to Intermediate II is shown in Scheme 3. ADiels-Alder reaction between styrene 19 and diene 20 providescyclohexene 21. Deprotection gives intermediate II. Styrene 19 and diene20 are commercially available, known in the literature, or prepared by avariety of methods known to those skilled in the art.

As illustrated in Scheme 4, the compounds of the present invention offormula I, wherein X is a bond, are made by reductive amination ofIntermediate II in the presence of amine HI using reagents such assodium cyanoborohydride or decaborane in solvents such asdichloromethane, tetrahydrofuran, or methanol to provide intermediateIV. The reaction is optionally conducted in the presence of a Lewisacid, such as titanium tetrachloride. The reaction may also befacilitated by adding an acid, such as acetic acid. In some cases,Intermediate III may be a salt, such as a hydrochloride ortrifluoroacetic acid salt, and in these cases it is convenient to add abase, generally N,N-diisopropylethylamine, to the reaction mixture. Theprotecting group is then removed with, for example, trifluoroacetic acidor methanolic hydrogen chloride in the case of Boc, to give the desiredamine I. The product is purified, if necessary, by recrystallization,trituration, preparative thin layer chromatography, flash chromatographyon silica gel, such as with a Biotage® apparatus, or HPLC. Compoundsthat are purified by HPLC may be isolated as the corresponding salt.Purification of intermediates is achieved in the same manner.

Compounds I of the present invention wherein X is not a bond may beprepared as described in Scheme 5. Intermediate IIc is treated with anagent such as an acyl chloride, sulfonyl chloride, carbamoyl chloride,alkyloxy or aryloxycarbonyl choride or an isocyante in the presence of abase such as triethylamine or N,N-diisopropylethylamine to giveintermediate IV. Deprotection provides compounds of formula I.

In some cases the product I or synthetic intermediates illustrated inthe above schemes may be further modified, for example, by manipulationof substituents on Ar, R³, or R⁴. These manipulations may include, butare not limited to, reduction, oxidation, alkylation, acylation, andhydrolysis reactions that are commonly known to those skilled in theart.

In some cases the order of carrying out the foregoing reaction schemesmay be varied to facilitate the reaction or to avoid unwanted reactionproducts. The following examples are provided so that the inventionmight be more fully understood. These examples are illustrative only andshould not be construed as limiting the invention in any way.

Intermediate I

tert-Butyl [(1S, 2R)-5-oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamateStep A: 8-(2,4,5-Trifluorophenyl)-1,4-dioxaspiro[4.5]decan-8-ol

A three neck flask (2 L) under an atmosphere of nitrogen with Mgturnings (9.8 g) was stirred for 15 rain and tetrahydrofuran (90 m1L)was added and stirring continued for an additional 15 min.1-Bromo-2,4,5-trifluorobenzene (85 g) was dissolved in tetrahydrofuran(340 mL). A portion of this solution (75 m1L) was added to the stirredmagnesium turnings and then heated to 50° C. The rest of the solutionwas added and stirring continued at the same temperature for anadditional 1 h. The reaction mixture was cooled to 40° C., a solution of1,4-dioxaspiro[4.5]decan-8-one (57.3 g) in tetrahydrofuran (275 mL) wasadded, and stirring continued for 10 h. The reaction mixture was pouredinto saturated aqueous ammonium chloride solution (970 mL) and extractedwith toluene (700 mL). The organic layer was washed with water (3×700mL), dried over anhydrous sodium sulfate, filtered and evaporated toyield the title compound as a red-orange oil which was used in the nextstep without further purification.

Step B: 8-(2,4,5-Trifluorophenyl)- 1 4-dioxaspiro[4.5]dec-7-ene

To a round-bottomed flask (3 L) under nitrogen atmosphere equipped witha Dean-Stark trap, toluene (350 mL), para-toluenesulphonic acidmonohydrate (p-TSA) (1 g) and8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]decan-8-ol (94.2 g) wereadded and the mixture was refluxed overnight. Additional p-TSA (1 g) wasadded. Refluxing was continued overnight and then the reaction wasstirred at room temperature for two more days. The reaction mixture wastreated with 0.1 N aqueous sodium hydroxide solution (500 mL) andextracted with heptanes (500 m-L). The organic layer was washed withwater (3×500 mL), dried over anhydrous sodium sulfate, filtered andevaporated to yield crude product which was purified by columnchromatography (silica gel, gradient 2% to 40% ethyl acetate inheptanes) to yield the title compound.

Step C: 8-(2,4,5-Trifluorophenyl)-1,4-dioxaspiro[4.5]decane

A solution of 8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-ene inmethanol (240 mL) and ethyl acetate (5 mL) was treated with 10%palladium on carbon (7.0 g) and stirred under an atmosphere of hydrogengas (40 psig) overnight. The reaction mixture was filtered over Celite.The filtrate was concentrated and chromatographed (silica gel, gradient5-7% ethyl acetate in hexane) to yield the title compound.

Step D: 4-(2,4,5-Trifluorophenyl)cyclohexanone

8-(2,4,5-Trifluorophenyl)-1,4-dioxaspiro[4.5]decane was added to asolution of 1,4-dioxane (600 mL), water (160 mL) and concentratedsulfuric acid (160 mL) and the resultant mixture was stirred for one h.The solution was then mixed with water (1 L) and extracted withdichloromethane (1 L). The organic layer was washed with water, driedover anhydrous magnesium sulfate, filtered and evaporated to yield thetitle compound as a white solid.

Step E:Triisopropyl{[4-(2,4,5-trifluorophenyl)cyclohex-1-en-1-yl]oxy}silane

A three-neck flask (1 L) containing a stirred solution of4-(2,4,5-trifluorophenyl)cyclohexanone (15.8 g) in dichloromethane (160mL) under a nitrogen atmosphere was cooled to 0° C. and then treatedwith triethylamine (22 mL) followed by triisopropylsilyltrifluoromethanesulfonate (25.4 g) while maintaining the temperaturebelow 5° C. The solution was stirred at 0° for 30 min and then allowedto rise to ambient temperature over a period of 0.5 h. It was thentreated with saturated aqueous ammonium chloride solution. The organiclayer was separated, dried over anhydrous magnesium sulfate andevaporated. The crude product was chromatographed (silica gel, 3% etherin hexane) to yield the title compound.

Step F:{[3-Azido-4-(2,4,5-trifluorophenyl)cyclohex-1-en-1-yl]oxy}(triisopropyl)silane

In a three-neck flask, a stirred solution oftriisopropyl{[4-(2,4,5-trifluorophenyl)cyclohex-l-en-1-yl]oxy}silane(26.06 g, 0.068 mol) in dichloromethane (260 mL) was cooled to −15° C.and treated with iodosobenzene (19.5 g, 0.089 mol) in four portionsfollowed by azidotrimethylsilane (24 mL, 0.116 mol) while maintainingthe temperature below −10° C. Stirring was continued for 1.5 h. Thereaction mixture was allowed to warm to room temperature briefly, thencooled again back to −15° C. and filtered. The filtrate was evaporatedunder vacuum below 25° C. to give the title compound which was useddirectly in the next step.

Step G: trains6-(2,4,5-Trifluorophenyl)-3-[(triisopropylsilyl)oxy]cyclohex-2-en-1-amine

To a stirred solution of{[3-azido-4-(2,4,5-trifluorophenyl)cyclohex-1-en-1-yl]oxy}(triisopropyl)silane(48.2 g) in ether (280 mL) at 0° C. in a three-neck flask (1 L) wasadded lithium aluminum hydride (1M in ether, 85 mL) while maintainingthe temperature below 5° C. The reaction mixture was allowed to warm upto room temperature after completion of addition of the hydride. Themixture was transferred to ice with some saturated aqueous ammoniumchloride solution and filtered. The residue was washed with ethylacetate (1 L), and the organic layer separated, dried over anhydroussodium sulfate, filtered, and concentrated. The residue waschromatographed (silica gel, gradient 10-35% ethyl acetate in heptane)to yield the faster eluting cis- and the slower-eluting trans6-(2,4,5-trifluorophenyl)-3-[(triisopropylsilyl)oxy]cyclohex-2-en-1-amine.

Step H: trans tert-Butyl(6-(2,4,5-trifluorophenyl)-3-[(triisopropylsilyl)oxy]cyclohex-2-en-1-yl)carbamate

To a round bottomed flask (500 mL) containingtrans-6-(2,4,5-trifluorophenyl)-3-[(triisopropylsilyl)oxy]cyclohex-2-en-1-amine(8.77 g) dissolved in dichloromethane (80 mL), triethylamine (3.5 mL)and di-tert-butyl dicarbonate (1.0M in tetrahydrofuran, 25 mL) wereadded. The mixture was stirred overnight. The next day the solution wasevaporated and the concentrated red residue was chromatographed (silicagel, gradient 25-85% dichloromethane—hexane) to yield the desiredproduct.

Step I: tert-Butyl [(1S,2R)5-oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate

To a round-bottomed flask (500 mL) containing trans tert-butyl(6-(2,4,5-trifluorophenyl)-3-[(triisopropylsilyl)oxy]cyclohex-2-en-1-yl)carbamate(10.7 g) dissolved in tetrahydrofuran (100 mL), tetrabutylammoniumfluoride (1M in tetrahydrofuran, 26 mL) was added and the mixture wasstirred for 1 h. The solution was concentrated to a dark brown oil andpurified by chromatography (silica gel, gradient 20%-40% ethyl acetatein hexane) to yield the product as a mixture of enantiomers. HPLC usinga chiral AD column (12% isopropanol in heptane) gave the title compoundas the slower eluting isomer. LC/MS 227.1 (M+1).

Intermediate 2

Benzyl [(1S, 2R)-5-Oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamateStep A: Methyl 8-oxo-1,4-dioxaspiro[4.5]decane-7-carboxylate

To a stirred solution of 1,4-cyclohexanedione monoethylene ketal (1.00g, 6.4 mmol) in dimethyl carbonate (6 mL) at room temperature was addedsodium hydride (0.31 g, 7.7 mmol). The mixture was heated at 80° C. for20 min and then diluted with dry toluene (20 mL). The mixture wasstirred for an additional 3 h at 80° C., cooled to room temperature,quenched with water, and then extracted with dichloromethane. Theorganic phase was dried over anhydrous sodium sulfate and evaporated toyield the crude product which was purified by Biotage® chromatography(silica gel, ethyl acetate in hexanes gradient 30-42%) to yield thetitle compound.

Step B:7-(Methoxycarbonyl)-8-{[(trifluoromethyl)sulfonyl]oxy}-4-oxa-1-oxoniaspiro[4.5]dec-7-ene

To a stirred solution of methyl8-oxo-1,4-dioxaspiro[4.5]decane-7-carboxylate (2.14 g, 10 mmol) indichloromethane (22 mL) at −78° C. was added N,N-diisopropylethylamine(8.5 mL, 48.8 mmol). After 10 min, trifluoromethanesulfonic anhydride(2.0 mL, 12 mmol) was added dropwise. The resulting mixture was stirredovernight while the temperature was allowed to warm up to roomtemperature. The mixture was diluted with ethyl acetate and washed with10% aqueous citric acid solution. The organic phase was dried overanhydrous sodium sulfate and evaporated to yield the title compound.

Step C: Methyl8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-ene-7-carboxylate

To a stirred solution of7-(methoxycarbonyl)-8-{[(trifluoromethyl)sulfonyl]oxy}-4-oxa-1-oxoniaspiro[4.5]dec-7-ene(5.65 g, 16.0 mmol) dissolved in N,N-dimethylformamide (190 mL) wereadded aqueous sodium carbonate solution (2.0M, 20 mL, 39.0 mmol) and2,4,5-trifluorophenylboronic acid (4.11 g, 23.4 mmol). The resultingmixture was degassed and treated with PdCl₂(dppf)([1,1′-bis(diphenylphosphino)-ferrocene] dichloropalladium(II), complexwith dichloromethane (1:1), 1274 mg). The resulting mixture was stirredunder a nitrogen atmosphere at room temperature overnight, filtered overCelite, diluted with ethyl acetate and washed with water. The organicphase was dried over anhydrous sodium sulfate, evaporated and the crudeproduct was purified by chromatography on a Biotage® system (silica gel,ethyl acetate in hexanes gradient 30-50%) to yield the title compound.

Step D: Methyl8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]decane-7-carboxylate

To a stirred solution of methyl8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-ene-7-carboxylate(1.93 g, 5.9 mmol) in methanol (50 mL) was added magnesium (1.43 g, 59mmol), and the mixture was refluxed overnight under nitrogen atmosphere.The white precipitate that formed was filtered over Celite, and thefiltrate was evaporated under reduced pressure to yield the titlecompound.

Step E: trans Methyl8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]decane-7-carboxylate

To a stirred solution of8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]decane-7-carboxylate (1.95g, 5.9 mmol) in methanol (50 mL) was added sodium methoxide (0.5M inmethanol, 14.2 ml, 7.1 mmol), and the resulting solution was refluxedovernight under a nitrogen atmosphere, cooled to room temperature andevaporated to yield the crude product which was purified bychromatography on a Biotage® system (silica gel, ethyl acetate inhexanes gradient 25-54%) to yield the title compound containing some cisisomer.

Step F: trans8-(2,4,5-Trifluorophenyl)-1,4-dioxaspiro[4.5]decane-7-carboxylic acid

A stirred solution of trans8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]decane-7-carboxylate fromStep E (1.82 g, 5.5 mmol) dissolved in tetrahydrofuran (11 mL) andmethanol (22 mL) was treated with aqueous lithium hydroxide solution(1.OM, 18.5 mL) and the mixture was stirred at room temperatureovernight. The reaction solution was acidified with hydrochloric acid(1N) to pH 1 and extracted with ethyl acetate. The organic phase waswashed by saturated brine solution, dried over anhydrous sodium sulfateand evaporated to yield the title compound.

Step G: Benzyl[8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-yl]carbamate

A stirred solution of trans8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]decane-7-carboxylic acid(500 mg, 1.29 mmol) in toluene (20 mL) was treated withdiphenylphosphoryl azide (0.33 mL, 1.55 mmol), triethylamine (0.22 mL,1.55 mmol) and anhydrous benzyl alcohol (0.33 mL, 3.2 mmol) at roomtemperature under a nitrogen atmoshpere. After heating at 90° C. for 2days, the reaction mixture was evaporated under reduced pressure and theresidue was diluted with ethyl acetate and washed with saturated aqueoussodium bicarbonate solution. The organic phase was dried over anhydroussodium sulfate and evaporated to yield the crude product which waspurified by chromatography on a Biotage® system (silica gel, ethylacetate in hexanes gradient 25-40%) to yield the title compound.

Step H: Benzyl [(7S,8R)-8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-yl]carbamate

Benzyl [8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-yl]carbamate(528 mg) was resolved by HPLC using a chiral AD column (13% isopropanolin heptane) to give benzyl [(7S,8R)-8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-yl]carbamate asthe slower eluting enantiomer.

Step I: Benzyl [(1S,2R)-5-oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate

To a stirred solution of benzyl[(7S,8R)-8-(2,4,5-trifluorophenyl)-1,4-dioxaspiro[4.5]dec-7-yl]carbamate(315 mg, 0.75 mmol) in sulfuric acid (15 mL, 1:1 in water) was added1,4-dioxane (30 mL). The mixture was stirred at room temperature for 1h. The resulting mixture was poured into water (70 ml) and extractedwith dichloromethane. The organic layer was dried over anhydrous sodiumsulfate and evaporated to yield the title compound. LC/MS 378.0 (M+1).

Intermediate 3

tert-Butyl [(1S,2R)-5-oxo-2-(2,5-difluorophenyl)cyclohexyl]carbamate

The title compound was prepared from 1-bromo-2,5-difluorobenzenegenerally following the procedures outlined for the synthesis ofIntermediate 1. LC/MS 209.1 (M+1).

Intermediate 4

3-(Trifluoromethyl)-5,6,7,8-tetrahydro[,1,2,4]triazolo[4,3-α]pyrazine,hydrochloride saltStep A: Bis(2,2,2-trifluoroaceto)hydrazide

Hydrazine (20.1 g, 35 wt % in water, 0.22 mol) was mixed with 310 mL ofacetonitrile. 31.5 g of ethyl trifluoroacetate (0.22 mol) was added over60 min. The internal temperature was increased to 25° C. from 14° C. Theresulting solution was aged at 22 -25° C for 60 min. The solution wascooled to 7° C. 17.9 g of 50 wt % aqueous NaOH (0.22 mol) and 25.3 g ofchloroacetyl chloride (0.22 mol) were added simultaneously over 130 minat a temperature below 16° C. When the reaction was complete, themixture was vacuum distilled to remove water and ethanol at 27˜30° C.and under 26˜27 in Hg vacuum. During the distillation, 720 mL ofacetonitrile was added slowly to maintain constant volume (approximately500 mL). The slurry was filtered to remove sodium chloride. The cake wasrinsed with about 100 mL of acetonitrile. Removal of the solventafforded the desired bishydrazide. ¹H-NMR (400 MHz, DMSO-d₆): δ 4.2 (s,2H), 10.7 (s, 1H), and 11.6 (s, 1H) ppm.

Step B: 5-(Trifluoromethyl)-2-(chloromethyl)-1,3,4-oxadiazole

Bishydrazide from Step A (43.2 g, 0.21 mol) in acetonitrile (82 mL) wascooled to 5° C. Phosphorus oxychloride (32.2 g, 0.21 mol) was added,maintaining the temperature below 10° C. The mixture was heated to 80°C. and aged at this temperature for 24 h. In a separate vessel, 260 mLof isopropyl acetate and 250 mL of water were mixed and cooled to 0° C.The reaction slurry was charged to the quench keeping the internaltemperature below 10° C. After the addition, the mixture was agitatedvigorously for 30 min, the temperature was increased to room temperatureand the aqueous layer was cut. The organic layer was then washed with215 mL of water, 215 mL of 5 wt % aqueous sodium bicarbonate and finally215 mL of 20 wt % aqueous brine solution. HPLC assay yield after work upwas 86-92%. Volatiles were removed by distillation at 75-80 mm Hg, 55°C. to afford an oil which could be used directly in Step C withoutfurther purification. Otherwise the product can be purified bydistillation to afford the 1,3,4-oxadiazole. ¹H-NMR (400 MHz, CDCl₃): δ4.8 (s, 2H) ppm.

Step C: N-[(2Z)-Piperazin-2-ylidene]trifluoroacetohydrazide

To a solution of ethylenediamine (33.1 g, 0.55 mol) in methanol (150 mL)cooled at −20° C. was added distilled oxadiazole from Step B (29.8 g,0.16 mol) while keeping the internal temperature at −20° C. After theaddition was complete, the resulting slurry was aged at −20° C. for 1 h.Ethanol (225 mL) was then charged and the slurry slowly warmed to −5° C.After 60 min at −5° C., the slurry was filtered and washed with ethanol(60 mL) at −5° C. The product was obtained as a white solid.

Step D:3-(Trifluoromethyl)-5,6,7,8-tetrahydro[2,4]triazolo[4,3-α]pyrazine,hydrochloride salt

A suspension of the amidine from Step C (27.3 g, 0.13 mol) in 110 mL ofmethanol was warmed to 55° C. 37% Hydrochloric acid (11.2 mL, 0.14 mol)was added over 15 min at this temperature. During the addition, allsolids dissolved resulting in a clear solution. The reaction was agedfor 30 min. The solution was cooled down to 20° C. and aged at thistemperature until a seed bed formed (10 min to 1 h). 300 mL of methyltert-buyl ether (MTBE) was charged at 20° C over 1 h. The resultingslurry was cooled to 2° C., aged for 30 min and filtered. Solids werewashed with 50 mL of ethanol:MTBE (1:3) and dried under vacuum at 45° C.to afford the title compound; m.p. 264° C. (decomp); electrospray massspectrum: 192 (M+). ¹H-NMR (400 MHz, DMSO-d₆): δ 3.6 (t, 2H), 4.4 (t,2H), 4.6 (s, 2H), and 10.6 (b, 2H) ppm.

Intermediate 5

2-(Trifluoromethyl)-5,6,8-tetrahydroimidazo[1,2-α]pyrazineStep A: 2-(Trifluoromethyl)imidazo[1,2-α]pyrazine

To a solution of 2-aminopyrazine (5.25 g, 55.2 mmol) in ethanol (120 mL)was added 1-bromo-3,3,3-trifluoroacetone (5.73 mL, 55.2 mmol). Thereaction was stirred at reflux for 20 h. After evaporation of solvent,the residue was partitioned between ethyl acetate and saturated aqueoussodium bicarbonate solution. The aqueous layer was extracted three timeswith ethyl acetate. The combined organic phase was washed with saturatedbrine solution, dried over magnesium sulfate and concentrated. Theresidue was purified by flash chromatography (silica gel, 1:1 ethylacetate:hexane, then 100% ethyl acetate) to give the title compound as asolid. ¹H NMR (500 MHz, CDCl₃): 6 8.02 (m, 2H), 8.13(m, 1H), 9.22 (s,1H). ESI-MS 188 (M+1).

Step B: 2-(Trifluoromethyl)-5,6,7,8-tetrahydroimidazo[1,2-α]pyrazine

To a solution of 2-(trifluoromethyl)imidazo[1,2-α]pyrazine (2.0 g, 10.46mmol, from Step A) in methanol (100 mL) was added 10% palladium oncarbon (400 mg). The mixture was stirred under atmospheric hydrogen atambient temperature for 14 h. The mixture was filtered through Celiteand washed three times with methanol. The filtrate was concentrated andpurified by flash chromatography (silica gel, 10% methanol in ethylacetate, then 15% methanol in chloroform with 1% aqueous ammoniumhydroxide) to give the title compound as a solid. ¹H NMR (500 MHz,CDCl₃): δ 1.93 (bs, 1H), 3.26 (t, 2H, J=5.5 Hz), 3.99 (t, 2H, J=5.5 Hz),4.10 (s, 1H), 7.16 (s, 1H). ESI-MS 192 (M+1).

Intermediate 6

(3R)-Hexahydro-3-methyl-2H-1,4-diazepin-2-one hydrochlorideStep A: Methyl N-(tert-butoxycarbonyl)-N-(2-cyanoethyl)-D-alaninate

To a stirred suspension of D-alanine methyl ester hydrochloride (2.0 g)and 5N aqueous sodium hydroxide solution (2.9mL) in water (15 mL) at 0°C, acrylonitrile (1.1 mL) was added. The resultant mixture was stirredat 70° C. for 3.5 h and cooled to room temperature. Di-tert butyldicarbonate (30 mL) was added and the reaction mixture stirred for twodays. The reaction mixture was diluted with saturated aqueous sodiumbicarbonate solution and extracted with ethyl acetate. The organic layerwas separated, washed with brine, dried over anhydrous sodium sulfateand concentrated. The residue was purified by flash columnchromatography (silica, ethyl acetate/hexane 2:3) to yield methylN-(tert-butoxycarbonyl)-N-(2-cyanoethyl)-D-alaninate.

Step B: Methyl N-(3-aminopropyl)-N-(tert-butoxycarbonyl)-D-alaninate

To a solution of methylN-(tert-butoxycarbonyl)-N-(2-cyanoethyl)-D-alaninate (1.5 g) in ethanol(80 mL) and chloroform (1.4 mL) was added platinum oxide (350 mg), andthe reaction mixture was stirred over an atmosphere of hydrogen for 16h. The mixture was filtered through Celite, and the Celite washed withmethanol and dichloromethane. The filtrate was concentrated to givemethyl N-(3-aminopropyl)-N-(tert-butoxycarbonyl)-D-alaninate as an oilyresidue.

Step C: tert-Butyl(2R)-Hexahydro-2-methyl-3-oxo-1H-1,4-diazepine-1-carboxylate

To a 2M solution of trimethylaluminum in dichloromethane (30 mL) wasadded slowly a solution of methylN-(3-aminopropyl)-N-(tert-butoxycarbonyl)-D-alaninate (11.5 g) indichloromethane. The reaction mixture was stirred at room temperaturefor four days and then poured into a flask containing 30 g of Celite.The mixture was stirred and quenched by the slow addition of about 10 mLof saturated aqueous ammonium chloride solution. Sodium sulfate (20 g)and methanol (50 mL) were added. The mixture was stirred for 1 h, thenfiltered. The solids were washed with 5% methanol/dichloromethane. Thefiltrate was concentrated. The residue was purified by flashchromatography (silica gel, eluting sequentially with 4, 6, 7 and 12% of10:1 methanol/aqueous concentrated ammonium hydroxide indichloromethane) to provide the title compound. LC/MS 228.9 (M+1).

Step D: (3R)-Hexahydro-3-methyl-2H-1.4-diazepin-2-one hydrochloride

tert-Butyl (2R)-hexahydro-2-methyl-3-oxo-1H-1,4-diazepine-1-carboxylateobtained in the previous step was dissolved in 4M hydrogen chloride indioxane and evaporated after 2.5 h to yield the hydrochloride salt ofthe desired compound.

Intermediate 7

2-(Trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[1,5-α]pyrazineStep A: 2.2,2-Trifluoro-N-pyrazin-2-ylacetamide

To a slightly heterogeneous solution of aminopyrazine (22.74 g, 239mmol) and triethylamine (36.66 mL, 263 mmol) in dichloromethane (400 mL)was added trifluoroacetic anhydride (50.20 g, 239 mmol) dropwise at 0°C. The solution was stirred at 0° C. for 1 h and at ambient temperaturefor 2 h. Filtration of the resultant white precipitate followed bywashing with dichloromethane afforded the title compound as a whitesolid. ¹H NMR (500 MHz, CD₃OD): 6 8.44-8.46 (m, 2H), 9.33 (d,1H, J=1.4Hz); LC/MS 192 (M+1).

Step B: 2,2,2-Trifluoro-N′-hydroxy-N-pyrazin-2-ylethanimidamide

To a suspension of 2,2,2-trifluoro-N-pyrazin-2-ylacetamide (14.56 g,76.26 mmol, from Step A) in dichloroethane (325 mL) was addedphosphorous pentachloride (421.73 g, 99.13 mmol) portionwise. Themixture was refluxed for 5 h. After evaporation of dichloroethane theresidue was suspended in tetrahydrofuran (325 mL). To the above mixturewas added 50% aqueous hydroxylamine (20 mL) dropwise. After stirring atambient temperature for 2 h, the mixture was partitioned between ethylacetate and aqueous sodium bicarbonate. The aqueous layer was extractedthree times with ethyl acetate. The combined organic layers were washedwith brine and dried over anhydrous magnesium sulfate. Concentrationgave the title compound as a yellow solid. ¹H NMR (500 MHz, CD₃OD): δ8.04 (m, 2H), 8.17 (s, 1H). LC/MS 207 (M+1).

Step C: 2-(Trifluoromethyl)[1,2,4]triazolo[1,5-α]pyrazine

A mixture of 2,2,2-trifluoro-N′-hydroxy-N-pyrazin-2-ylethanimidamide(10.5 g, 50.97 mmol, from Step B) and polyphosphoric acid (80 mL) washeated to 150° C. with stirring for 18 h. The solution was added to iceand neutralized by addition of ammonium hydroxide. The dark aqueoussolution was extracted three times with ethyl acetate, washed withbrine, and dried over anhydrous magnesium sulfate. Concentrationfollowed by flash chromatography (50% then 100% ethyl acetate/hexane)afforded the title compound as a yellow solid. ¹H-NMR (500 MHz, CDCl₃):δ 8.42 (d, 1H, J=4.6 Hz), 8.67 (dd, 1H, J=1.4 and 4.6 Hz), 9.47 (d, 1H,J=1.4 Hz). LC/MS 189 (M+1).

Step D:2-(Trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[1,5-α]pyrazine

2-(Trifluoromethyl)-[1,2,4]triazolo[1,5-α]pyrazine (340 mg, 1.81 mmol,from Step C) was hydrogenated under atmospheric hydrogen with 10%palladium on carbon (60 mg) as a catalyst in ethanol (10 mL) at ambienttemperature for 18 h. Filtration through Celite followed byconcentration gave a dark colored oil. Flash chromatography (100% ethylacetate, then 10% methanol/dichloromethane) gave the title compound as awhite solid. ¹H-NMR (500 MHz, CDCl₃): δ 1.80 (br, 1H), 3.40 (t, 2H,J=5.5 Hz), 4.22-4.26 (m, 4H); LC/MS 193 (M+1).

Intermediate 8

5 6,7,8-Tetrahydro[1,2,4]triazolo[1,5-α]pyrazineStep A: N,N-Dimethyl-N′-pyrazin-2-ylimidoformamide

A solution of 2-aminopyrazine (16.45 g) in dimethylformamidedimethylacetal (22.4 g) was refluxed at 85° C. for 3 h, evaporated underreduced pressure, and used in the next step without furtherpurification.

Step B: N-Hydroxy-N′-pyrazin-2-ylimidoformamide

A solution of N,N-dimethyl-N′-pyrazin-2-ylimidoformamide (189 g) fromStep A in tetrahydrofuran (400 mL) was treated drop wise with 50%aqueous solution of hydroxylamine (245.7 mL) at 0° C., then warmed up to80° C. for 2.5 h. Tetrahydrofuran was removed by rotoevaporation and theresulting aqueous mixture kept cold in a refrigerator. The resultingsolid was filtered and rinsed with cold diethyl ether to yield thedesired product.

Step C: [2,4]Triazolo[1,5-α]pyrazine

To stirred Eaton's reagent (850 mL), solidN-hydroxy-N′-pyrazin-2-ylimidoformamide (167.45 g) was added in smallportions while maintaining the temperature below 60° C. The reactionmixture was heated at 80° C. overnight, then poured over ice (3000 g)and neutralized by the dropwise addition of pre-cooled concentratedammonium hydroxide (1.7 L) to pH 9, while maintaining the temperaturebelow 50° C. The mixture was extracted with ethyl acetate (5×4L), driedover anhydrous sodium sulfate, filtered and evaporated to 500 mL. Theresulting mixture was filtered and crystals of the title compound werecollected.

Step D: 5,6,7,8-Tetrahydro[1,2,4]triazolo[1.5-α]pyrazine

A mixture of [1,2,4]triazolo[1,5-α]pyrazine (10 g) in ethanol (150 mL)and 10% Pd-C (3 g) was stirred under a hydrogen atmosphere overnight andfiltered over Celite®. The filtrate was evaporated and the residuepurified by column chromatography (silica, 10% methanol/dichloromethane)to yield 5,6,7,8-tetrahydro[1,2,4]triazolo[1,5-α]pyrazine. LC-MS 125.1(M+1).

Intermediate 9

2-(Trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidineStep A:7-(Phenylmethyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-4-ol

To a solution of sodium ethoxide, prepared from 3.2 g (133 mmol) ofsodium metal and 200 mL of absolute ethanol, at ambient temperature wasadded 8.3 g (74 mmol) of trifluoroacetamidine followed by 17.8 g (60mmol) of ethyl 1-benzyl-3-oxopiperidine-4-carboxylate hydrochloride inportions over 15 min. The reaction mixture was stirred at ambienttemperature for 1 h, then heated at reflux for 30 h. The mixture wasconcentrated in vacuo. The resultant red foam was partitioned between300 mL of 1N aqueous sodium hydroxide solution and 300 mL of ether. Theaqueous layer was washed with 300 mL of ether and the combined etherphases were extracted with 50 mL of 1N aqueous sodium hydroxidesolution. The combined aqueous phases were cooled in an ice-water bathand neutralized to pH 7 with concentration hydrochloric acid. The solidswere collected, washed with water, and dried in vacuo to give the titlecompound as a beige solid, which was used as is. An analytical samplewas prepared by recrystallization from isopropanol to give a whitesolid. LC-MS 310.0 (M+1).

Step B:4-Chloro-7-(phenylmethyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine

A mixture of 29.6 g (95.7 mmol) of7-(phenylmethyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidin-4-oland 53 mL of phenylphosphonic dichloride in a 250-mL round bottom flaskwas heated at 150° C. After 2 h, the mixture was cooled to ambienttemperature and poured onto 400 g of ice, transferring with about 500 mLof ethyl acetate. The aqueous layer was neutralized with solid sodiumbicarbonate and the layers separated. The aqueous layer was extractedwith two portions of ethyl acetate. The combined organics were washedsequentially with saturated aqueous sodium bicarbonate solution andbrine, dried over sodium sulfate and concentrated to give a brown solid.The solid was boiled in 2 L of hexane with charcoal, filtered, andconcentrated in vacuo to give the title compound as a yellow solid.LC-MS 328.3 (M+1).

Step C: 2-(Trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine,hydrochloride

A flask containing a solution of 23.4 g (71.41 mmol) of amine from StepB in 285 mL of ethyl acetate and 530 mL of methanol was purged withnitrogen, and 2 g of 10% Pd/C was added. The mixture was stirred under 1atm of hydrogen until the reaction was judged complete by TLC analysis(about 7.5 h total). The mixture was filtered through Celite, and theCelite washed with methanol. The organics were concentrated in vacuo andthe resultant pale yellow oil was triturated with 400 mL of ether.Crystals formed and an additional 400 mL of ether was added. The mixturewas stirred overnight. The resultant solid was collected by filtrationand dried in vacuo to give 16.3 g of off-white crystals that containedan impurity by TLC analysis. The crystals were dissolved in a minimumamount of methanol. Ether was added to turbidity and the mixture waswarmed on a steam bath. Crystals formed and the mixture was allowed tocool to ambient temperature and aged for 30 min. It was then filtered.The collected solid was dried in vacuo to give the title compound as awhite crystalline solid. LC-MS 203.8 (M+1).

EXAMPLE 1

[(1S,2R,5S)-5-[3-(Trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-α]pyrazin-7-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]amine,bis trifluoroacetic acid saltStep A: tert-Butyl[(1S,2R,5S)-5-[3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-α]pyrazin-7-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamateand tert-butyl[(1S,2R,5R)-5-[3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-α]pyrazin-7-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate

A solution of tert-butyl[(1S,2R)-5-oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate(Intermediate 1, 70 mg) and3-(trifluoromethyl)-5,6,7,8-tetrahydro-1,2,4-triazolo[4,3-α]pyrazine(Intermediate 4, 39 mg) in dichloromethane (5 mL) was treated withtitanium tetrachloride (1M in dichloromethane, 0.1 mL). The reactionmixture was stirred at room temperature overnight and then treated witha solution of sodium cyanoborohydride (38 mg) in methanol (2 mL). Afterstirring for 15 min, the solution was brought to pH 13 with 5N aqueoussodium hydroxide solution and extracted with ethyl acetate. The organicphase was dried and concentrated. Purification by preparative TLC(silica, 6% of a solution of methanol containing 10% ammonium hydroxidein dichloromethane) yielded the TLC faster eluting (1S,2R,5R) isomer andthe slower eluting (1S,2R,5S) isomer.

Step B:[(1S,2R,5S)-5-[3-(Trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-α]pyrazin-7-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]amine,bis trifluoroacetic acid salt

tert-Butyl[(1S,2R,5S)-5-[3-(trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-α]pyrazin-7-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate,the slower eluting isomer from Step A, was dissolved in trifluoroaceticacid/dichloromethane (1:1) and evaporated after 1 h. The residueobtained as such was purified by preparative TLC (silica gel,methanol/ammonium hydroxide/dichloromethane 9:1:90) to yield the titlecompound. LC/MS 420.0 (M+1). ¹H NMR (600 MHz, CD₃OD): δ 7.41 (m, 1H),7.22 (m, 1H), 4.22 (t, 2H, J=5.5 Hz), 4.11 (AB, 2H, J=15.6 Hz), 3.59 (m,1H), 3.19 (m, 2H), 3.04 (tt, 1H, J=11.9,3.4 Hz), 2.97 (br m, 1H), 2.38(dm, 1H, J=11.8 Hz), 2.09 (dm, 1H, J=12.3 Hz), 2.00 (dq, 1H, J=13.8,3:6Hz), 1.76 (m, 1H), 1.67 (q, 1H, J=11.8 Hz), 1.58 (dq, 1H, J=3.4,12.3Hz).

EXAMPLE 2

[(1S,2R,5R)-5-[3-(Trifluoromethyl)-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-α]pyrazin-7-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]amine,bis-trifluoroacetic acid salt

Essentially following the procedure outlined in Example 1, Step B, thefaster eluting (1S,2R,5R) isomer from Example 1, Step A was converted tothe title compound. ¹H NMR (600 MHz, CD₃OD): δ 7.35 (m, 1H), 7.16 (m,1H), 4.28 (m, 2H), 4.04 (d, 1H, J=15.7 Hz), 3.96 (d, 1H, J=15.7 Hz),3.77 (dt, 1H, J=2.7,11.8 Hz), 3.16 (m, 1H), 3.09 (br, 1H), 3.06 (m, 1H),2.88 (quintet, 1H, J=3.0 Hz), 2.54 (dq, 1H, J=14.0,2.9 Hz), 2.28 (dm,1H, J=14.1 Hz), 1.98 (qm, 1H, J=12.4 Hz), 1.78 (ddd, 1H, J=2.6,13.5,14.4Hz), 1.74 (m, 1H), 1.70 (m, 1H).

Following essentially the procedures outlined for Example 1, theExamples listed in Table 1 were prepared. TABLE 1

MS Example R¹ NR⁴(XR³) (M + 1) 3 2-F, 5-F

402.2 4 2-F, 5-F

338.1 5 2-F, 4-F, 5-F

347.1 6 2-F, 4-F, 5-F

420.1 7 2-F, 4-F, 5-F —NMeCH₂Ph 349.2 8 2-F, 4-F, 5-F

415.1 9 2-F, 4-F, 5-F

419.1

EXAMPLE 10

[(1S,2R,5S)-5-(5,6-Dihydro[1,2,4]triazolo[1,5-α]pyrazin-7(8H)-yl)-2-(2,4,5-trifluorophenyl)cyclohexyl]amine

To a solution of tert-butyl[(1S,2R)-5-oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate(Intermediate 1, 200mg) in anhydrous methanol (8.0 mL) under nitrogenwas added 5,6,7,8-tetrahydro[1,2,4]triazolo[1,5-α]pyrazine hydrochloride(55 mg), triethylamine (0.081 mL) and decaborane (22 mg). After stirringat 50° C. for 24 h, the reaction mixture was concentrated andchromatographed by preparative TLC (silica gel, 1:4:95 ammoniumhydroxide/methanol/dichloromethane). The slow moving desired compoundwas recovered, stirred in 4N hydrogen chloride in 1,4-dioxane for 50min, and concentrated. The residue was purified by preparative TLC(silica, 1:9:90 ammonium hydroxide/methanol/dichloromethane) to affordthe title compound. LC-MS 352.1 (M+1).

EXAMPLE 11

[(1S,2R,5S)-5-[2-(Trifluoromethyl)-5,8-dihydropyrido[3,4-d]pyrimidin-7(6H)-yl]-2-(2,4,5-trifluorophenyl)cyclohexyl]amine,dihydrochloride

To a solution of tert-butyl[(1S,2R)-5-oxo-2-(2,4,5-trifluorophenyl)cyclohexyl]carbamate(Intermediate 1, 75 mg) in anhydrous methanol (3.0 mL) under nitrogenwas added 2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[3,4-d]pyrimidine(45 mg) and decaborane (8 mg). After stirring at room temperature for 2h, the reaction mixture was concentrated and chromatographed bypreparative TLC (silica gel, ethyl acetate/dichloromethane 3:7). Theslow moving desired compound was recovered, stirred in 1N HCl inmethanol for 1 h, and concentrated. The residue was purified bypreparative TLC (silica, 1:9:90 ammoniumhydroxide/methanol/dichloromethane) to afford the desired product, whichwas converted to its dihydrochloride salt by stirring in 2 mL of 1Nmethanolic hydrogen chloride and evaporating under reduced pressure.LC-MS 431.2 (M+1).

Example of a Pharmaceutical Formulation

As a specific embodiment of an oral pharmaceutical composition, a 100 mgpotency tablet is composed of 100 mg of any of Examples 1-11, 268 mgmicrocrystalline cellulose, 20 mg of croscarmellose sodium, and 4 mg ofmagnesium stearate. The active, microcrystalline cellulose, andcroscarmellose are blended first. The mixture is then lubricated bymagnesium stearate and pressed into tablets.

While the invention has been described and illustrated with reference tocertain particular embodiments thereof, those skilled in the art willappreciate that various adaptations, changes, modifications,substitutions, deletions, or additions of procedures and protocols maybe made without departing from the spirit and scope of the invention.For example, effective dosages other than the particular dosages as setforth herein above may be applicable as a consequence of variations inresponsiveness of the mammal being treated for any of the indicationswith the compounds of the invention indicated above. The specificpharmacological responses observed may vary according to and dependingupon the particular active compounds selected or whether there arepresent pharmaceutical carriers, as well as the type of formulation andmode of administration employed, and such expected variations ordifferences in the results are contemplated in accordance with theobjects and practices of the present invention. It is intended,therefore, that the invention be defined by the scope of the claimswhich follow and that such claims be interpreted as broadly as isreasonable.

1. A compound of the formula I:

or a pharmaceutically acceptable salt thereof; wherein each n isindependently 0, 1, 2, or 3; X is selected from the group consisting ofa bond, C=O, SO₂, CO₂, CONH and CONR²; Ar is phenyl unsubstituted orsubstituted with one to five R¹ substituents; each R¹ is independentlyselected from the group consisting of halogen, cyano, hydroxy, C₁₋₆alkyl, unsubstituted or substituted with one to five halogens, C₁₋₆alkoxy, unsubstituted or substituted with one to five halogens, carboxy,C₁₋₆ alkyloxycarbonyl, amino, NHR², NR²R², NHSO₂R², NR²SO₂R², NHCOR²,NR²COR², NHCO₂R², NR²CO₂R², SO₂R², SO₂NH₂, SO₂NHR², and SO₂NR²R²; eachR² is independently C₁₋₆ alkyl, unsubstituted or substituted with one tofive substituents independently selected from halogen, CO₂H, and C₁₋₆alkyloxycarbonyl; each R³ and R⁴ is independently selected from thegroup consisting of hydrogen, C₁₋₁₀ alkyl, wherein alkyl isunsubstituted or substituted with one to five substituents independentlyselected from halogen or hydroxy, C₂₋₁₀ alkenyl, wherein alkenyl isunsubstituted or substituted with one to five substituents independentlyselected from halogen or hydroxy, (CH₂)_(n)-aryl, wherein aryl isunsubstituted or substituted with one to five substituents independentlyselected from R⁶, (CH₂)_(n)-heteroaryl, wherein heteroaryl isunsubstituted or substituted with one to three substituentsindependently selected from R⁶, (CH₂)_(n)-heterocyclyl, whereinheterocyclyl is unsubstituted or substituted with one to threesubstituents independently selected from oxo and R⁶, (CH₂)_(n)-C₃₋₆cycloalkyl, wherein cycloalkyl is unsubstituted or substituted with oneto three substituents independently selected from R⁶; wherein anyindividual methylene (CH₂) carbon atom in (CH₂)_(n) is unsubstituted orsubstituted with one to two groups independently selected from halogen,hydroxy, C₁₋₄ alkyl, and C₁₋₄ alkoxy, wherein alkyl and alkoxy areunsubstituted or substituted with one to five halogens; or, when X is abond, R³ and R⁴ together with the nitrogen atom to which they areattached form a 4- to 7-membered monocyclic heterocyclic ring optionallycontaining an additional heteroatom selected from O, S, N, and NH, saidheterocyclic ring being unsubstituted or substituted with one to threeR^(a) substituents independently selected from oxo, hydroxy, halogen,C₃₋₆ cycloalkyl, C₁₋₄ alkoxy, and C₁₋₄ alkyl, wherein cycloalkyl, alkyland alkoxy are unsubstituted or substituted with one to five fluorines;and said heterocyclic ring being optionally fused with a 5- to6-membered saturated, partially unsaturated, or aromatic carbocyclicring or a 5- to 6-membered saturated, partially unsaturated, or aromaticheterocyclic ring containing one to three heteroatoms selected from O,S, N, and NH, said fused ring being unsubstituted or substituted withone to four R^(b) substituents independently selected from oxo, hydroxy,amino, halogen, C₃₋₆ cycloalkyl, C₁₋₄ alkyl, and C₁₋₄ alkoxy, whereincycloalkyl, alkyl and alkoxy are unsubstituted or substituted with oneto five fluorines; each R⁶ is independently selected from the groupconsisting of hydroxy, halogen, cyano, CO₂H, NR⁷R⁸, CONR⁷R⁸, OCONR⁷R⁸,SO₂NR⁷R⁸, SO₂R⁹, NR¹⁰SO₂R⁹, NR¹⁰CONR⁷R⁸, NR¹⁰COR⁹, NR¹⁰CO₂R⁹, C₁₋₆alkyloxycarbonyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxyare unsubstituted or substituted with one to five halogens; R⁷ and R⁸are each independently selected from the group consisting of hydrogen,(CH₂)_(n)-phenyl, (CH₂)_(n)-C₃₋₆ cycloalkyl, and C₁₋₆ alkyl, whereinalkyl is unsubstituted or substituted with one to five substituentsindependently selected from halogen and hydroxy and wherein phenyl andcycloalkyl are unsubstituted or substituted with one to fivesubstituents independently selected from halogen, hydroxy, C1-6 alkyl,and C1-6 alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens; or R⁷ and R⁸ together with thenitrogen atom to which they are attached form a heterocyclic ringselected from azetidine, pyrrolidine, piperidine, piperazine, andmorpholine wherein said heterocyclic ring is unsubstituted orsubstituted with one to three substituents independently selected fromhalogen, hydroxy, C1-6 alkyl, and C1-6 alkoxy, wherein alkyl and alkoxyare unsubstituted or substituted with one to five halogens; each R⁹ isindependently C₁₋₆ alkyl, wherein alkyl is unsubstituted or substitutedwith one to five substituents independently selected from halogen andhydroxyl; and R¹⁰ is hydrogen or R⁹.
 2. The compound of claim 1 whereineach R¹ is independently selected from the group consisting of fluorine,chlorine, bromine, methyl, trifluoromethyl, and trifluoromethoxy.
 3. Thecompound of claim 1 wherein X is a bond and R³ and R⁴ together with thenitrogen atom to which they are attached form an optionally fusednitrogen-containing heterocyclic ring selected from the group consistingof:

wherein said heterocyclic ring is unsubstituted or substituted withR^(a) and R^(b) substituents as defined in claim
 1. 4. The compound ofclaim 3 wherein said nitrogen-containing heterocyclic ring is selectedfrom the group consisting of:

unsubstituted or substituted with R^(a) and R^(b).
 5. The compound ofclaim 1 of structural formulae Ia and Ib having the indicatedstereochemical configuration at the two stereogenic cyclohexane carbonatoms marked with an *:


6. The compound of claim 5 of structural formula Ia having the indicatedabsolute stereochemical configuration at the two stereogenic cyclohexanecarbon atoms marked with an


7. The compound of claim 5 of structural formulae Ic and Id having theindicated stereochemical configuration at the three stereogeniccyclohexane carbon atoms marked with an *:


8. The compound of claim 7 of structural formula Ic having the indicatedabsolute stereochemical configuration at the three stereogeniccyclohexane carbon atoms marked with an *:


9. The compound of claim 8 wherein X is a bond and R³ and R⁴ togetherwith the nitrogen atom to which they are attached form an optionallyfused nitrogen-containing heterocyclic ring selected from the groupconsisting of:

wherein said heterocyclic ring is unsubstituted or substituted withR^(a) and R^(b).
 10. The compound of claim 5 of structural formulae Ieand If having the indicated stereochemical configuration at the threestereogenic cyclohexane carbon atoms marked with an *:


11. The compound of claim 10 of structural formula Ie having theindicated absolute stereochemical configuration at the three stereogeniccyclohexane carbon atoms marked with an *:


12. The compound of claim 11 wherein X is a bond and R³ and R⁴ togetherwith the nitrogen atom to which they are attached form an optionallyfused nitrogen-containing heterocyclic ring selected from the groupconsisting of:

wherein said heterocyclic ring is unsubstituted or substituted withR^(a) and R^(b).
 13. The compound of claim 8 which is selected from thegroup consisting of:

or a pharmaceutically acceptable salt thereof.
 14. A pharmaceuticalcomposition which comprises a compound of claim 1 and a pharmaceuticallyacceptable carrier. 15-16. (canceled)
 17. The pharmaceutical compositionof claim 14 additionally comprising metformin.
 18. A method for treatingnon-insulin dependent (Type 2) diabetes in a mammal in need thereofwhich comprises the administration to the mammal of a therapeuticallyeffective amount of a compound of claim 1.